DNA ties deceased Florida man to 1987 Broward murder, solving 38-year-old cold case
After nearly four decades, South Florida authorities say DNA evidence has finally solved the 1987 murder of Marilyn Decker — linking the crime to a Florida man with a long criminal record who died nearly 30 years ago.
The Davie Police Department said it has posthumously charged Donald Lawless in the case.
Victim's family waited years for answers
For most of that time, Gail DeMore and her family lived without answers about who killed her sister Marilyn Decker in October 1987. Now, detectives say ex-con Donald Lawless is the suspected killer. He died 30 years ago.
"It infuriates me that my sister's murderer, with such a long history of violent acts amongst innocent victims, was left unpunished," DeMore said.
Decker's body found in Davie canal
The crime happened on Oct. 22, 1987, in Davie. Decker, who was 28 years old, was found floating in a canal in the 3000 block of Flamingo Road with multiple stab wounds. Her cause of death was determined to be homicide by asphyxiation, also known as suffocation.
According to police, Lawless was 62 years old at the time of the crime. Marilyn's body was found floating in a canal off Flamingo Road, which was just two lanes at the time.
Detective: Decker killed elsewhere first
"The way she was killed, it was by strangulation and she was stabbed multiple times after she had already passed. We also believe she was killed elsewhere than she was dumped in a canal on Flamingo," said Detective Eddy Velazquez, one of the investigators who helped solve the case.
Davie police said that in the 1980s, multiple suspects were identified, but as evidence was collected and processed, there were negative results and the case remained unsolved.
Case went cold, then reopened
The investigation continued in 1995 with interviews and more scene items being processed. There were no active leads and more negative results, leaving the trail cold once again.
In 2021, the case was reopened by the Davie PD Cold Case Unit. Possible suspects were interviewed and family members spoke with detectives who had worked on the case previously. Police even featured the case on a Broward Crime Stoppers billboard.
DNA evidence leads to Lawless
"We processed the shirt and the towel, we found multiple hairs," Velazquez said. "We got DNA back," he continued. "We were able to get to Lawless."
Davie police said the hairs found in Decker's clothing revealed male DNA. That sample was analyzed by a genealogist, who eventually identified Lawless as a possible match.
Lawless, who would now be 100 years old, lived in Florida from the early 1980s through 1993 and had a criminal history dating back to the 1940s. He died in Ohio in 1995 and was cremated.
Davie police said they obtained DNA from a close relative of Lawless and matched it to the sample found on Decker's shirt.
The case was turned over to the Broward County State Attorney's Office, which determined there was enough evidence to charge Lawless with Decker's murder.
Detective suggests possible serial pattern
Velazquez said Lawless could be a serial killer.
"We found out areas like Fort Lauderdale, BSO, Hollywood had similar cases of women that were found dumped and kind of killed in a similar manner," he said.
Family finds purpose through tragedy
While it's tough for the family to still not have all the answers, the case inspired Marilyn's great niece, who was born years after the murder, to pursue a career in crime-solving.
"I plan on going to college I plan on studying and devoting my life to this. This is what I want to do, I'm dedicated to it," said Angelina DeMore.