'Killer clown' victim's son reflects on 33-year fight for justice

Watch ABC News "20/20" tonight at 9:00 p.m. ET/8:00 p.m. CT for an encore presentation of this report, which first aired May 5, 2023.

For over 30 years, the "killer clown" has captivated investigators, Florida residents and true crime followers around the world.

Marlene Warren, a mother of two, was shot and killed in front of her son by a clown who approached her door and gave her balloons and flowers.

While the scary situation made headlines at the time, and remained a major unsolved mystery for a decade, Warren's son Joey Ahrens told "20/20" in an exclusive interview that it left a hole in his heart that has never been filled.

"She was a great mother," Joe Ahrens told "20/20," in an exclusive interview. "She was charismatic. She was a person of love."

Ahrens' interview will be part of an extensive "20/20" airing Friday, May, 5 at 9 p.m. ET and streaming the next day on Hulu that looks at the 33-year-investigation.

Investigators announced a breakthrough in the case nearly six years ago saying new DNA evidence from mysterious hairs found in the getaway car and other clues directly pointed to Sheila Keen Warren, the second wife of Ahrens' stepfather. She pleaded guilty to second-degree murder last week.

"I never thought I was going to get a guilty [verdict]," Ahtens told "20/20" after the sentencing. "That was a shock. It just blew my mind."

On May 26, 1990, Marlene Warren was at her Wellington, Florida, home with Ahrens, who was 21 at the time, and several of his friends, according to investigators. At the time, she was living with her second husband, Michael Warren, who ran a used car lot and a rental car agency.

Ahrens said that he, his friends and his mother saw a white Chrysler LeBaron pull into the driveway just before 11 a.m. that day and someone dressed as a clown came to the front door with flowers and balloons.

One of the balloons said, "You're the Greatest," according to police.

"The last words I heard my mother say was, 'Oh, how pretty,' and bang," Ahrens said.

The clown escaped in the car, according to witnesses, and Warren died in the hospital two days later.

In the immediate aftermath of the murder, police were able to track the stores where the balloons, flowers and clown costume were purchased and Deborah Offerman, a store employee, told investigators that she remembered selling the clown costume, wig and other accessories to a woman who came to the store right before closing.

"'I need to buy a costume,' And I said, 'Can you come back tomorrow? We're closed,'" Offerman told "20/20" in a 2017 interview. "'No, I really need this tonight. I need to get a costume tonight,'" she said the customer told her.

Officers were alerted to an abandoned Chrysler LeBaron in a Winn-Dixie parking lot four days after the shooting. Inside they found what they called "trace evidence," including what law enforcement officers described as artificial orange-like fibers, that could have come from a clown wig.

They also discovered what appeared to be long brown strands of human hair, which would later be crucial to the case.

DNA analysis at the time wasn’t as advanced, and relevant DNA couldn’t be taken from hair.

Although Michael Warren was questioned by the police, he had an alibi as he was on his way to a Miami racetrack with friends at the time of the shooting. He denied having any involvement in the murder.

Friends and family told police that Michael Warren may have been having an affair with his employee Sheila Keen, who was a repossession agent.

Investigators did question Keen and Michael Warren about the affair but they both denied it.

The costume shop employees identified Keen Warren to the police as the woman who purchased the clown suit. Cops searched her home, but found no evidence to warrant an arrest.

Keen and Michael Warren would get married in 2002 and settle in Virginia, unbeknownst to most of their Florida friends and family. In the meantime, investigators could not find any more leads in the case.

Ahrens said the pain of his mother's death and that his family didn't get justice led him into a depression and alcohol addiction.

Eventually, he entered rehab and said his mental health has improved.

"I broke down, and I said, 'Enough is enough, I can't do this on my own,'" he said.

The case started to pick up traction in 2013 when new prosecutor Reid Scott revisited the forensic evidence found during the initial investigation.

Scott ordered that the hairs be tested using mitochondrial DNA analysis, which he told "20/20" is a "type of analysis that is conducted typically on older samples."

The more advanced analysis determined that the hair matched Keen Warren, according to investigators.

She would be arrested and extradited to Florida in Oct. 2017, charged with first-degree murder of Marlene Warren.

Michael Warren wasn't charged.

For five years, Keen Warren waited in jail for her trial to begin, as her attorney Greg Rosenfeld maintained her innocence and questioned the prosecutors' case.

Rosenfeld told "20/20" that he questioned the validity of DNA evidence and analysis, given that it was in storage for so long.

He also noted that Aherns and other witnesses initially claimed that the clown appeared to be a man.

"A clown costume does not disguise your gender. You can tell if a clown's a man or a woman, even with makeup on," he said.

Scott, however, reiterated the clues added up.

"Yes, it's circumstantial evidence, but an overwhelming amount of circumstantial evidence," he said.

In the meantime, Ahrens said he was sure that Keen Warren would face justice.

"Sheila Keen-Warren was the murderer of my mother. I was there, I saw her eyes. And I'll tell you. They're the eyes. I'll never forget them," he said.

But a few weeks before the trial was set to begin, Keen Warren made a shocking announcement -- she was going to make a plea deal with prosecutors.

The deal, which was announced on April 25, had Keen Warren plead guilty to second-degree murder in exchange for a 12-year sentence. Rosenfeld said that her five and a half years in custody would count towards that sentence and she could be released next year on good behavior.

"The defendant is pleading guilty because she's guilty and a factual basis does exist for the crime," Scott said.

Ahrens appeared via a video conference at the plea hearing and told the judge he accepted the conditions, but noted that he never once saw remorse from Keen Warren.

"My final conclusion was, I was going to be at peace with the outcome," he said. "Guilty or not, I was going to be okay."

A few days after the plea deal was finalized, Ahrens visited his mother's grave to give her a message.

"I was telling her we finally got truth. We finally got closure," he said.

ABC News' Meredith Deliso contributed to this report.