This story originally aired on Oct. 15, 2022.

A college professor, her boyfriend and a former psychologist — three friends in a small Georgia town got together one spring night to swim and play and listen to music. Marianne Shockley was a respected college professor and renown entomologist. By morning, she and the former psychologist, Clark Heindel, were dead. Only her boyfriend, Marcus Lillard, was alive.

"There is good and there is evil and that night … evil came to play," Lillard, the sole survivor, tells "48 Hours" contributor Jonathan Vigliotti in an exclusive interview.  

Charged with his girlfriend's murder, Lillard told investigators he had nothing to do with Marianne's death and a jury acquitted him. Her family doesn't believe him. So, what happened that night? 

A DEADLY NIGHT

It was nearing 3 a.m. on Mother's Day, May 12, 2019, when Baldwin County Sheriff's deputies stormed into Clark Heindel's house and found he'd killed himself with a shotgun.

DEPUTY (bodycam video): Sheriff's Office!

DEPUTY: Sheriff's Office!

DEPUTY: We're gonna need to get that gun away from him … his hand's still on it.

Only moments earlier, Heindel had called 911 asking paramedics to come to his home in Milledgeville, Georgia, and the scene was captured on police bodycams.

911 OPERATOR: 911.

CLARK HEINDEL: Yes, I need an ambulance.

Heindel said a friend of his, college professor Marianne Shockley, had seemingly drowned in his hot tub.

DEPUTY (bodycam audio): We gotta treat this like a crime scene.

Within hours, Marianne's death was being investigated as a homicide and authorities say they had two suspects: her boyfriend, Marcus Lillard, who was being held for questioning, and Heindel, a longtime resident of Milledgeville.  

Penny Dearmin: I think a lotta people do think that because Clark Heindel killed himself, he had some kind of involvement.

Penny Dearmin investigated the case on her podcast, Blood Town.

Penny Dearmin: I'm doing this podcast because I need to know what happened to her.

As it turns out, Dearmin had previously met Lillard.

Penny Dearmin: I met Marcus when I purchased my truck.

At the time, Marcus Lillard was working as a car and truck finance manager.

Jonathan Vigliotti: And what was your impression during that transaction?

Penny Dearmin: He was very nice. He was very personable, making jokes, making me feel very comfortable, very at ease … and I liked him right away.

Pretty much everyone agrees that Lillard, who was married and divorced twice, was a charmer. But, as Penny Dearmin later learned, that charm came with a reputation.

Penny Dearmin: He was definitely known as a ladies' man. Everyone, regardless of what they thought of him, knew that about him.

Marcus Lillard: … somehow God continued to send women my way that were way too good for me. And I would date 'em, and I'd take 'em for granted, one right after another. And it was — it was a steady pattern.

Carson Lillard: He's the most … charismatic — person I've ever met. I mean he's just got this kind of aura about him that sucks people in.

Carson is Marcus' 23-year-old-son.

Carson Lillard: Anywhere he wanted to go, there was a woman there that he could shack up with and stay with.

And eventually, Marianne also fell under his spell. The two had met in the late 1990s when they were students at Georgia College in Milledgeville and working at the same local restaurant.

Jonathan Vigliotti: Was there a spark in that moment?

Marcus Lillard: No. I was a kid, man. I was probably 17, and she would have been 20 … I was a little, you know little — little wormy guy.

Ayla Crippen: I thought he was fine. I mean, nothing stood out to me to be irregular about him.

Ayla Crippen is Marianne's younger sister. She went to the same college as Marianne and Lillard.

Ayla Crippen: He … dated one of my best friends and roommates at the time. Um, they didn't date for very long. She said she got a weird vibe from him.

Lillard admits drugs got in the way of his college education and he dropped out.

Marcus Lillard: I just thought life was a party. And — I treated it as such.

Ayla Crippen: I never really thought about him again until Marianne started dating him, you know, two decades later.

The year was 2017. Lillard was on the road in Athens, Georgia. He knew Marianne lived there, so he invited her to lunch.

Marcus Lillard: I was on my motorcycle, we took a trip around Athens … we went to her home away from home, the … botanical gardens. … The motorcycle ride, I mean, that was s — it's as romantic as you can get for lunch time on a — on a Wednesday.

Some 20 years after they first met, Lillard says they clicked.

Marcus Lillard: We spent every possible moment together on the weekends.

Marianne enjoyed Lillard's company so much that she brought him along as her assistant on trips to China and Ecuador.

Jonathan Vigliotti: So, this is a very serious relationship.

Marcus Lillard: Absolutely, yeah, yeah … we were super in love with each other.

Ayla Crippen: ... to me, he was not relationship material. He's somebody that you go have a good time with, and then you'd send him on his way.

Crippen says the relationship seemed to suit Marianne's busy lifestyle. She'd been married and divorced three times and had two children. She had a PhD and was a star professor at the University of Georgia where she was known around campus as "Doc Shock." Her specialty was entomology — the study of insects.

Marianne liked everything about insects, including their taste.

MARIANNE SHOCKLEY (video): Ants taste like citrus. Some grain state bugs taste like cinnamon.

She embraced entomophagy—the eating of insects. And she believed bugs could be used as a protein source to help solve world hunger.

Shakara Maggitt was one of Marianne's students who became a true believer and something of a bug baker. At "48 Hours"' request, she brought some cricket brownie samples.

Jonathan Vigliotti: Let's dig in. Let's kind of try it. You can put … a few more crickets on mine. I'm not — I'm not squeamish.

Shakara Maggitt (topping a brownie with more crickets): OK, here (laughs).

Jonathan Vigliotti(holds up brownie):  … To Marianne.

Shakara Maggitt: To Marianne. Ooh, and it's so moist.

Jonathan Vigliotti: The brownie is perfectly cooked, perfectly baked. And the crickets add a little bit of added crunch.

Shakara Maggitt: Yes.

Maggitt says she could tolerate eating bugs more than she could tolerate Marcus Lillard.

Shakara Maggitt: I didn't particularly care for him. I couldn't really put my finger on it, but I didn't like him.

Carson Lillard could relate.

Carson Lillard: Nobody knows a father better than their own son.

He had warned Marianne that Marcus had a Jekyll and Hyde personality, largely because of drugs.

Carson Lillard: He was on cocaine my whole life.

And he cautioned her to be careful.

Carson Lillard: "… he's angry, and he's violent and … you're gonna see it."… "if I could tell you anything it -- it would just be to -- get away …"

A "CONFUSING AND DECEITFUL" NIGHT

On the afternoon of May 11, 2019, Marcus Lillard and Marianne Shockley were in a celebratory mood. The college school year had just ended and as seen in surveillance footage the couple went bar hopping in Milledgeville before heading over to Clark Heindel's house.

Marcus Lillard: … had a few beers, smoked a little pot, started listenin' to some music … had a couple more beers.

Lillard spoke to "48 Hours" from jail; he's been behind bars since Marianne's death. He told us about that night and how it all began as an impromptu jam session. Clark Heindel played the accordion and Marcus tried his hand at the conga drums, just as they had done in the past.

Marcus Lillard: We had stepped down from his porch and were gettin' ready to leave. And I said, "Hey Clark, I heard you got some acid." And he says, "No, but I've got some ecstasy."

Lillard says all three of them took the ecstasy pills — a drug that makes users feel euphoric but can also cause anxiety and paranoia.

Jonathan Vigliotti: What happened next?

Marcus Lillard: It got all fuzzy after that.  

Marcus Lillard: I was so out of it … I couldn't make a sentence, I couldn't speak.

But Lillard did later piece together a timeline and told investigators that he thought he and Marianne got into the hot tub around 9 p.m. Marcus said, at one point, he got out of the hot tub and Marianne begged him not to leave.

Marcus Lillard: She says, "Baby get — get back in this water with me right now."

Jonathan Vigliotti: … Was she afraid? Was she expressing any kinda concern —

Marcus Lillard: She had— she had — she had fear in her voice. And it was — it was definitely fear.

Lillard says it was not clear what Marianne was afraid of.

Jonathan Vigliotti: Why, in that moment, did you not turn back?

Marcus Lillard:  'Cause I'm an idiot.

DEPUTY to MARCUS LILLARD (bodycam video): Leave that right there. Don't touch nothin'.

Marcus initially told deputies that he went into the woods to collect firewood.

MARCUS LILLARD (bodycam video): I went over to get some wood to make firewood. I brought a whole bunch of stuff back …

But he later said the real reason he went into the woods was that he was trying to recreate a scene from a documentary called "The Last Shaman." While on drugs, the lead character takes part in bizarre rituals like being buried alive.

Marcus Lillard: I said, "I'm goin' to the woods to dig a hole."

Lillard says he went into the woods and simply laid down; for how long, he says he does not know.

Marcus Lillard: I can't remember anything past her saying, "Don't leave me."

Jonathan Vigliotti: What do you say to those who are hearing this story of a guy who has a history with drugs, who is claiming, you know, "I blacked out." Convenient, it sounds like.

Marcus Lillard: The devil was at work. I mean, everything that he could have possibly done to line this thing up to make it confusing and deceitful and — it was all there.

Jonathan Vigliotti: You emerge from the woods … What is the first thing you remember seeing, hearing?

Marcus Lillard: I didn't hear anything … I could see Marianne slumped down with her chin up to her nose under water.

CLARK HEINDEL (bodycam video): I — I'm sittin' down there (points to the end of the pool). Hanging out swimming at that end of the pool.

DEPUTY: OK.

CLARK HEINDEL: Shallow end.

DEPUTY: And she's in the hot tub. 

CLARK HEINDEL (affirms): Mm hmm.

DEPUTY: Do you know at what point you noticed she wasn't visible?

CLARK HEINDEL: I — I never saw that she wasn't visible. But I got up, I guess when he was coming back.

Lillard says he pulled Marianne out of the hot tub and placed her on the pool deck. In doing so, Marcus admits dropping Marianne who suffered a gash to her forehead. At that point, he says Heindel walked over.

Marcus Lillard: And he actually said, "Should we call 911? ..."

Jonathan Vigliotti: And what did you say?

Marcus Lillard: I said, "No, I think she'll be fine."

But Marianne was not fine. That gash on her head bled profusely and it appeared she was not breathing. Lillard and Heindel say they took turns giving her CPR but delayed calling 911.

Podcaster Penny Dearmin has her own theory about why Lillard did not immediately call police. In 2015, Marcus was convicted of selling marijuana and possessing methamphetamine and cocaine. He was still on probation for that crime.

Penny Dearmin: I would say that if you were an individual who's been in trouble with the law before and you're currently on probation, that you would be afraid to call 911.

Ayla Crippen: It makes my family so angry and so hurt … If he had a good heart, if he truly loved Marianne, he would've sacrificed anything to save her.

CLARK HEINDEL to 911:  Yes, I need an ambulance at …

It's unclear how much time had passed before Heindel called 911, but investigators believe Marianne had been dead for at least two hours before help arrived. The questions from deputies on the scene got much more pointed.

DEPUTY (bodycam video): If she's unconscious, y'all didn't think to call 911? If she's unconscious?

CLARK HEINDEL: It seemed like she was breathing.

Deputies decided to separate the men for further questioning. They put Marcus in a squad car.

DEPUTY (bodycam video): Marcus, OK. Policy says I have to put you in handcuffs any time I transport you, OK? Just place your hands behind your back for me, OK?

But, judging from the bodycam footage, deputies seemed to be having a hard time getting Heindel to cooperate.

DEPUTY (bodycam video): I done told him three times to stay off the pool … but he's insistin' to have his lawyer … Somethin'- somethin' is not right here, bro.

DEPUTY to CLARK HEINDEL:  Wait right there. It's a crime scene now, wait right there.
I asked you to wait back there, sir.

CLARK HEINDEL: What?

DEPUTY: I asked you to wait back there.

But then, the deputy watching Clark got a phone call, and Clark wandered off.

DEPUTY: We got a dead woman …

No one noticed that Clark had slipped into his house — not until deputies heard that shotgun go off and found his body.

DEPUTIES (bodycam video): Sheriff's Office!

DEPUTIES: Sheriff's Office!

DEPUTIES: Sheriff's Office!

DEPUTY: He's in the bathroom.

DEPUTY: In the bathroom?

DEPUTY: Yeah.

Ayla Crippen: … it tainted the case one hundred percent, because there weren't two people there that could say what happened. There was only one.

But investigators say Clark did leave behind a potential clue: a handwritten suicide note.

Marcus Lillard: And I just said, "Well, he — he had to have done it." … if that pill made me so stupid maybe it made him, for once in his life, a violent guy.

INVESTIGATORS FIND A KEY A PIECE OF EVIDENCE

Baldwin County Sheriff Bill Massee and Major Brad King say they still can't shake the unease they felt when they arrived at Clark Heindel's house on May 12, 2019 — during the early morning hours when Marianne Shockley was pronounced dead.

Sheriff Bill Massee: The feeling at this scene was totally different than any I'd ever been to … It was a very — a very strange, strange feeling that everybody noticed here.

Sheriff Massee remembers walking through Heindel's house when he spotted what turned out to be a handwritten suicide note on the kitchen counter.

Jonathan Vigliotti: This is the suicide note Clark wrote before taking his life?

Sheriff Bill Massee: That is the note, yes, that we found in the house.

Jonathan Vigliotti: He says, "I am very sorry. I don't know what happened with Marianne, but it was on my watch, and I am so sorry for the family and friends.

Massee says Heindel did not admit any guilt in the letter; it mostly instructed his heirs on what to do with his possessions. Marcus Lillard was now the only surviving witness from the scene that night.

Jonathan Vigliotti: Why was Clark allowed to go back into his home?

Sheriff Bill Massee: I'll be upfront with you. It was a violation of our policy and procedures.

Jonathan Vigliotti: How big of a mistake was that in this case?

Sheriff Bill Massee: Oh, it was a terrible mistake. Terrible mistake … It was a dramatic, a dramatic error in this case.

Soon after deputies discovered Heindel had taken his life, Lillard was brought in for questioning. Hours later he was interviewed by Michael Maybin, a special agent for the Georgia Bureau of Investigation, also known as the GBI. Maybin broke the news about Heindel's suicide.

AGENT MICHAEL MAYBIN: During — during the time that, I guess, you were in the back seat of the car, Clark went inside his house, and he committed suicide inside the house.

MARCUS LILLARD: Oh, s***. You're kiddin'.

AGENT MICHAEL MAYBIN: I'm not — I'm not kiddin'. Why — why would — why would he do that?

MARCUS LILLARD: I don't know. Maybe that'll shed some light, but ... I can't believe this. I would never in a million years guess he would do that.

Lillard immediately began speculating on what might have happened when he says he was in the woods and away from Marianne.

MARCUS LILLARD: There's a pretty good chance that Clark got in that hot tub with her … I'm gonna say there's a very high chance of that, I mean, a really high chance ...

AGENT MICHAEL MAYBIN: Help me out, man. Do you — do you think he did somethin' to her?

MARCUS LILLARD: I don't think she woulda did it to herself, and I know I didn't do anything …

The investigation was in its early stages and authorities weren't sure who or what to believe. Ayla Crippen found it impossible to believe her sister could drown in a hot tub. 

Ayla Crippen: Made no sense. Marianne was intelligent. Like, even if she was drinking in the hot tub, I just could not see that happening.

Almost immediately, investigators found out about Lillard's 2015 drug conviction. But they were also looking closely at Heindel, who was 69 years old and had his own issues.

Jonathan Vigliotti: And he had a bit of a — checkered past that really caught up with him and impacted his career?

Penny Dearmin: Yes, unfortunately he lost his license to practice psychology.

Podcaster Penny Dearmin says Heindel's license to practice psychology was revoked in 2017 after a former female patient filed a complaint with a state licensing board. She  claimed that Clark had engaged her in a sexual relationship and had given her marijuana.

Penny Dearmin: It's a pretty sordid tale.

But investigators could find no proof Heindel had done anything to Marianne. Sheriff Massee had known Clark for years and knew his son had died at the age of six from a rare form of cancer.

Sheriff Bill Massee: … losin' his psychology license, the death of a young son that had had him depressed for years, the embarrassment of it all, and it happened at his house.

After his son's death, Dearmin says Heindel took the first of several trips to Peru to work with shamans, much like the main character in "The Last Shaman" documentary.

By coincidence, Lillard says he and Heindel discussed that film on the night Marianne died. And in another bizarre twist, Lillard says Heindel found some hydrangea branches and shook them around Marianne's body.  

Sheriff Bill Massee: It was— ritualistic, or a séance, or somethin' …

Clark, who had opened a local yoga studio in recent years, had a lot of friends and supporters, including Lillard's son who began seeing Clark for therapy when he was only 14 years old.

Carson Lillard: I did love Clark and I still do. And I think I didn't realize how much he meant to me until he was gone.

Carson Lillard says that as soon as he heard Marianne was dead, he pinned the blame on his father whom he describes as a "malignant narcissist."

Carson Lillard: … he was headed towards destruction and was determined to bring somebody with him.

And Carson Lillard wasn't the only person who claimed Marcus had violent tendencies.

Sheriff Bill Massee: I was at my desk at the office and a young lady called me, extremely upset, and she said, "Sheriff Massee, Marianne Shockley didn't drown." She said, "Marcus choked her to death."

MARCUS LILLARD'S PAST REEMERGES 

Soon after Marianne Shockley was declared dead in the early morning hours of Mother's Day, May 12, 2019, Sheriff Bill Massee received that phone call from an ex-girlfriend of Marcus Lillard's who said she strongly suspected that Marcus had choked Marianne.

Sheriff Bill Massee: She said, "The same thing happened to me a long time ago when I was at a low point in my life," and she said he choked her havin' sex.

News had spread through word of mouth in the small town that Marianne had died in a hot tub, and Marcus was in jail.

Sheriff Bill Massee: I — I asked if she'd come give us a statement and she did.

Marcus Lillard's ex-girlfriend told investigators that Marcus had a choking fetish and that it was a regular part of their sex life.

GBI AGENT: How many times do you think you and Marcus had sex?

MARCUS LILLARD EX-GIRLFRIEND: Maybe 100 times. Maybe more than that.

GBI AGENT: How many times do you think choking was involved?

MARCUS LILLARD EX-GIRLFRIEND: I would say at least 30 times.

The woman said the erotic choking was consensual, but one time she says Lillard went too far.

MARCUS LILLARD EX-GIRLFRIEND (to GBI Agent): He choked me long enough to where I lost consciousness, and my body crumpled to the floor, and he just left me there.  

Lillard says his ex-girlfriend was exaggerating but he didn't deny choking her during sex.

Marcus Lillard: It was really more of a place to put your hands for control … Just a little light pressure to the carotid arteries to — you know, that was — that was really about it. There was never any pressure here. (He touches his throat) The pressure was here. It was not that. It was blown way outta proportion.

Lillard said he only tried choking Marianne one time and not on the night she died. He said she told him she didn't like it and he never tried it again. Ayla Crippen does not believe him.  

Ayla Crippen: I believe that they were having sex, and he choked her, and that is what caused her death.

GBI agents had first interviewed Lillard on Mother's Day morning and later placed him in custody on a probation hold stemming from his 2015 drug conviction. The following day, Monday, May 13, 2019, the autopsy results came in and investigators felt they were damning.

Sheriff Bill Massee: We were notified by the medical examiner that it was a classic case of strangulation … busted blood vessels in her eyes and … had nothing to do with any drowning.

Medical Examiner Dr. Melissa Sims-Stanley wrote that Marianne "died as a result of asphyxia due to strangulation. The manner of death … is best classified as homicide."

Given the results of the autopsy and the information from Lillard's ex-girlfriend, authorities say Lillard became the focus of the investigation. Hours after getting those autopsy results, GBI agent Michael Maybin requested another interview with Marcus, and he agreed. Again, he did not request a lawyer — at least at first.

AGENT MICHAEL MAYBIN: Strangulation is what killed her, OK …  and … you need to tell me what the hell happened because you know, and we need to talk about it.

MARCUS LILLARD: I don't know.

AGENT MICHAEL MAYBIN: Yes, you do.

MARCUS LILLARD: If I knew I woulda told you immediately.

Agent Maybin accuses Lillard of lying.

MARCUS LILLARD: So, I need to get a lawyer at this point, 'cause I mean you — you've already got your mind made up, you already — you already got your mind made up.

AGENT MICHAEL MAYBIN: Yep, I do … Well, you're under arrest for murder, I'll tell you that.

It was only one day after Marianne's death when Marcus Lillard was charged with her murder. He was formally indicted nearly two years later, in March 2021, and charged with four counts: felony murder, aggravated assault, involuntary manslaughter, and reckless conduct. He was ordered held without bond.

Ayla Crippen: It made sense that she was not responsible for her own death. Because I know my sister. She wasn't a careless person … did it make me feel better? No. Because now I know that someone took her from us.

Lillard sat in jail; months turned into years. Sheriff Massee says investigators vetted Clark Heindel and cleared him as a suspect. And as the trial approached, Lillard settled on Matt Tucker as his defense attorney.

Matt Tucker: And he just says, "I'm not gonna admit to anything I didn't do."

Largely because of COVID, nearly three years went by before Marcus Lillard stood trial for the murder of Marianne Shockley, but on April 4, 2022, his trial began at the Baldwin County Courthouse.

Assistant District Attorney Tammy Coffey laid out what the prosecution believes happened between Marcus and Marianne on the night she died.

Tammy Coffey: After they got in the hot tub, I think that they engaged in sex. I think he choked her. I think he choked her too hard and for too long.

Assistant District Attorney Nancy Malcor told "48 Hours" there was no clear evidence of sexual activity because Marianne's body had been in the hot tub for a prolonged period of time. Meanwhile, GBI agents had been busy talking to former sex partners of Lillard to determine if he had choked them. It turns out GBI agents found eight women.

MARCUS LILLARD EX-GIRLFRIEND #1:  I went out with Marcus a few times back in the fall of 2016 … One night we were having sex … and he put his hands around my neck.

DEPUTY: You said he did choke you at times?

MARCUS LILLARD EX-GIRLFRIEND #2: Mm-hmm (affirms).

MARCUS LILLARD EX-GIRLFRIEND #3: He did try to choke me. That was something he was into. I stopped him twice. It's not something that I'm into. I don't like it. It scares me.

Prosecutors put six of the women on the stand. The women testified Marcus choked them or attempted to choke them during sex.

And two of those witnesses told jurors Marcus had choked them until they passed out.

Matt Tucker: All of it was consensual … "They're still alive. So, I mean, how is it even relevant?"

But Ayla Crippen thinks their testimony was relevant and demonstrates how callous — and dangerous — Lillard could be.

Ayla Crippen: It's one thing to gamble with your own life, you know. You wanna do drugs, if you wanna choke yourself out, I mean, OK … and one of his girlfriends, he just told her to shut up. So that showed a disregard for women period.

The medical examiner testified to her findings, but Tucker noticed that the autopsy revealed the hyoid bone in Marianne's neck was intact and not broken. Some experts, including a surgeon Tucker consulted, consider that unusual in a strangulation case.

Matt Tucker: And he said, "That's what you need to explore. Find out why it wasn't broken. If somebody was to strangle … Marianne, why didn't it break?"

Tucker suggested to Dr. Sims-Stanley that perhaps whoever killed Marianne was too old or not strong enough to break that bone. He asked: could that person be 70 years of age?

Matt Tucker: And she said, "Yes," before she realized what she was saying. Clark was 69 at the time.

Tucker says that shows Clark, nearly three decades older than Marcus, could have been Marianne's killer. But would this juror agree?

Tyisha Davis: I was not there to prosecute Clark. I was there to find whether Marcus Lillard was guilty or not.

ACCIDENT OR MURDER?

As Marcus Lillard's trial progressed, defense attorney Matt Tucker floated the theory that Clark Heindel strangled Marianne after she rebuffed his sexual advances. It was a scenario that Lillard said had haunted him while he was behind bars.

Marcus Lillard: My theory for the better part of the three years was that he took a shot at her while she was alone, and she rejected him.

Prosecutors say there is no evidence Heindel did anything to Marianne, and they insist Lillard was the killer.

Tammy Coffey: In the autopsy— it shows manual strangulation … it was deliberate … the muscles themselves were severely damaged.

Marcus Lillard: I didn't — I didn't strangle her.

Jonathan Vigliotti: What do you say to people who are convinced you killed Marianne.

Marcus Lillard: I've been defending myself for so long, I'm not even really concerned what they think …

At trial, prosecutors Tammy Coffey and Nancy Malcor put Marianne's sister Ayla Crippen on the stand, and she talked about a private letter found in Marianne's house.

AYLA CRIPPEN (in court): The letter was her being reflective on her relationships and how … she had selected guys to date or to spend time with that were not good for her.

NANCY MALCOR: Did she mention anyone by name?

AYLA CRIPPEN: She did … and that was Marcus … she wrote, "When he does white lady, he gets violent."… the white lady, you know, I understood that to be cocaine.

Tests show that Lillard did have cocaine in his system the night Marianne died but could not pinpoint when he had taken the drug. As for that private letter —

NANCY MALCOR (in court): What did you do with it?

AYLA CRIPPEN: I gave it to my dad.

Crippen testified that her father burned the letter, leading Matt Tucker to question her memory.

MATT TUCKER (in court): You don't recall what the beginning of this letter started as?

AYLA CRIPPEN: I do not.

Matt Tucker: She swore up and down she read it. But three years ago, how do you remember what was in there?

Tucker offered jurors a second explanation for Marianne's death — a theory now embraced by Lillard, who no longer blames Heindel. 

Marcus Lillard: I think the ecstasy and the hot tub killed her.

Marcus Lillard: I feel like in my-- in my heart of hearts, that the medical examiners made a mistake.

Lillard's lawyer tried to get the medical examiner to admit Marianne could have died because of the amount of ecstasy and alcohol in her system coupled with the heat of the hot tub. Ecstasy is also known as MDMA.

Matt Tucker: "Now, ma'am, it's true that this hot tub was 107. They're only supposed to be 104 … That didn't have a factor with the body temperature bein' that high, with havin' the high levels of MDMA in her system, with them bein' drinking all day … this had nothing to do with it?"

Matt Tucker: And she was like, "No." She just disregarded that immediately.

But the medical examiner's own autopsy revealed that Marianne had cardiomegaly, an enlarged heart, which is a condition that medical experts say could lead to sudden cardiac death.

"48 Hours" had some questions and sent all the autopsy information to Dr. Greg Davis, a forensic pathologist not involved with the case. After reviewing the documents, he said that it was "possible" Marianne was strangled but, "A valid competing cause of death is sudden cardiac death due to mixed drug intoxication, a lethal mix of MDMA, alcohol, and marijuana with a contribution from underlying heart disease."

He said there was "no way" he would have called Marianne's death a "homicide." If it were up to him, he wrote, he'd classify her manner of death as "undetermined." But no medical experts testified for the defense. No one did, not even Marcus Lillard.

Matt Tucker: He wanted to testify bad. He wanted to get across, but I didn't think it'd be productive.

The trial moved swiftly. Jury selection started on a Monday and by late Friday afternoon April 8, 2022, the case went to the jury.

Jonathan Vigliotti: Time to deliberate. What are you thinking?

Marcus Lillard: I had peace, man. I had peace over — over the — really the whole thing.

Deliberations began and ended just like that.

Jonathan Vigliotti: Less than an hour goes by; there's a verdict.

Matt Tucker: 38 minutes.

Tyisha Davis: My first impression was he did it. He committed this murder. And whatever they tell me … it's not gonna prove to me that he didn't do it.

Tyisha Davis was juror No. 11.

Jonathan Vigliotti: Why did you think that?

Tyisha Davis: Because the professor was his girlfriend. And Clark Heindel was a 70-something-year-old man. He couldn't have murdered her. And I just — knew Marcus did it. I just knew he did it.

The top charge was felony murder, and the verdict was not guilty. Verdicts on the other charges followed in quick succession.

Carson Lillard: And it's just not guilty, not guilty, not guilty, not guilty. With each one … my heart just kinda sunk lower and lower.

Carson Lillard: I thought there was no way that he could get off.

Ayla Crippen: We were in utter shock. … Everyone was shocked. And, of course, I look over at Marcus and he's got a smirk on his face, and my blood was boiling.

How does Tyisha Davis explain her change of heart?

Tyisha Davis: I felt like the prosecuting attorney, she painted the picture that Marcus Lillard was a womanizer. He was a narcissist. But … they didn't prove that he was a killer.

Jonathan Vigliotti: What do you think happened to Maryanne Shockley that night?

Tyisha Davis: I don't know what happened … that frustrated me because we don't know what happened to her. Or if she really was strangled, if she died from strangulation … Who strangled her?

Jonathan Vigliotti: So, it sounds like — you even question if there was a murder in the first place.

Tyisha Davis: I had my doubts about that.

Judge Alison Burleson also had doubts, but they were of a different nature.

JUDGE ALISON T. BURLESON: Mr. Lillard, I've come to quite a different conclusion than what the jury has come to. It is quite clear to this court that the only person you were concerned with that night May 11, 2019, was yourself.

She immediately found that Marcus violated his probation for that 2015 drug conviction and he was remanded to prison.

Marcus Lillard: My conscience is very clear when it comes to Marianne. Do I miss Marianne? Yeah. I was lucky to get (voice breaks) that time with her that I did. And I cherish that.

Ayla Crippen: I think of Marianne every single day. I have her name on my bracelet … I'm wearing her earrings right now … Marianne was the most beautiful spirit.

Ayla Crippen: She worked hard … She cared about things that other people didn't care about. The teeny, weeny creatures that keep us alive, that keep our world turning.

Marcus Lillard could remain in prison until October 2030, but it's likely he'll be released sooner.

Marianne Shockley's children settled a wrongful death lawsuit against Clark Heindel's estate for $500,000. There was no admission of liability or fault.

This story discusses suicide. If you or someone you know is having thoughts of suicide, please contact the Suicide & Crisis Lifeline at 988.

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Produced by Paul LaRosa. Elizabeth Caholo and Ryan Smith are the development producers. Morgan Canty is the associate producer. Jordan Kinsey is the field producer. Doreen Schechter, George Baluzy and James Taylor are the editors. Anthony Batson is the senior broadcast producer. Nancy Kramer is the executive story editor. Judy Tygard is the executive producer.  

In:
• 48 Hours
• Marcus Lillard
• Marianne Shockley

Jonathan Vigliotti

Jonathan Vigliotti is a CBS News correspondent based in Los Angeles. He previously served as a foreign correspondent for the network's London bureau.

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