They also had Publix employees report that 90 minutes before the shooting a woman matching her description bought flowers and balloons like the kind the shooter left behind at the crime scene.
And perhaps the biggest discovery back then: Orange wig fibers found during a search of Keen's apartment appeared quite similar to those found in the getaway car.
But prosecutors determined it wasn't enough to file charges. Without DNA technology to solidly link Keen to the car via the hair strand, the evidence was boxed up for storage and the case languished for over two decades. The murder weapon and clown costume were never found.
REOPENING COLD CASE
In 2014, the sheriff's office received a $125,000 federal grant to reopen the investigation. A task force with members of the state attorney's office and the FBI began reinterviewing witnesses.
They also learned that Michael Warren and Sheila Keen had a Las Vegas wedding, several years after his release from prison on multiple charges of racketeering and odometer fraud. Authorities had examined his business dealings after his former wife's murder.
Records show that over a period of several months from late 2015 to early 2016, the FBI conducted new DNA testing and analyses of the hair and fibers in evidence.
In August 2017, prosecutors took their findings to a Palm Beach County grand jury, which returned an indictment of Sheila Keen Warren for the murder of Marlene Warren.
Without giving specifics, lead Detective Paige McCann then told reporters that the DNA results made all the difference. A person's DNA is a unique genetic fingerprint, which can be lifted from surfaces and analyzed.
"In cold cases we have a big puzzle," McCann said. "A lot of it was already filled in by the thorough investigation done by the initial detectives, and we just needed a few little pieces of the puzzle. And we were able to do that with new technologies and DNA."