Transcript for Accused killer clown could face the death penalty

Back now with new developments in that cold case involving a killer clown. ABC's Linzie Janis is here with the story. Good morning, Linzie. Reporter: Good morning, Michael. This case haunted a family and a Florida community for nearly 30 years. Now a woman accused of dressing up as a clown and killing her lover's wife is finally in custody. Authorities say they are seeking the maximum punishment. This morning, Sheila keen Warren could be facing the death penalty after police say she nearly got away with murder. We filed notice of intent to seek the death penalty in this case. Reporter: The 54-year-old wife and stepmother charged in a bizarre 27-year-old cold case. Like a scene straight out of the Hollywood film "It." I'm pennywise. Reporter: This is the woman who detectives say dressed as a clown back in 1990. Police say keen Warren pulled up to the Florida home of her boyfriend's wife dressed up as a clown complete with an Orange wig and white face paint. Handed her a bouquet of flowers and two balloons, then shot her at point blank range. I really don't want to talk. Reporter: The victim's son Joe home at the time of the murder. Watching the clown calmly driving away in this white convertible. Any murder is horrific. It doesn't matter wearing a clown costume or not. Reporter: Marlene Warren dying two days later. Investigators quickly zeroing in on keen Warren an employee at her husband's used car dooelership and detectives looking into rumors of an affair between the two. Police even finding fibers from a bright Orange wig at keen Warren's home. But there was never enough evidence to arrest her. Then three years ago detectives re-opening the investigation with the help of new DNA testing after learning that keen Warren married the victim's husband Michael in 2002. These technological advances helped crack the case and hopefully will bring justice to the family of Marlene Warren. Reporter: Last week police finally arresting their suspect. Marlene Warren's parents saying they're relieved. Justice will end it all here and that's all that really counts. Reporter: Sheila keen Warren was extradited from Virginia where she was living with her husband Michael for years being held without bond and is expected to plead not guilty. She vehemently denies any involvement. Dan Abrams back for more. Wow, 27 years after the fact. And they have viewed her as a suspect since 1991. They were even publicly naming her as a possible suspect but they go back in 2014, armed with new DNA evidence, they go and interview new witnesses and they now believe they're able to get identifying witnesses who can say she's the one who bought the balloons from me and the flowers 90 minutes before this happened. She's the one who bought a clown suit from me a couple days earlier so now they believe they've linked her to the clown suit, to the flowers, to the balloons, you throw DNA evidence on that and motive which is amazing. They didn't know that these two are gotten married. That gets to my next question. The husband not charged but not in the clear either. Not at all. They're continuing the investigation. But the fact that they didn't know that these two were married until they re-opened this investigation in 2014 is amazing and I'm sure the investigators suddenly said wait a second. These two got married? So he is definitely still being investigated as part of this and we'll see what they turn up.

This transcript has been automatically generated and may not be 100% accurate.