Cold Case Solved 1987
Nearly four decades after a young woman’s body was discovered floating in a Davie canal, police say they’ve finally solved the brutal 1987 murder of 28-year-old Marilyn Decker. The Davie Police Department announced on October 30, 2025, that DNA evidence and advanced genealogical testing have linked a deceased man, Donald Lawless, to Decker’s killing, closing one of South Florida’s most haunting cold cases.
The 1987 Discovery
On the morning of October 22, 1987, a passerby spotted Decker’s body in a canal along the 3000 block of Flamingo Road in Davie, Florida. Investigators quickly determined that Decker had been stabbed multiple times and asphyxiated before being dumped into the water. The Broward County Medical Examiner ruled her death a homicide. Despite collecting evidence and interviewing potential witnesses, detectives were unable to identify a suspect, and the case eventually went cold.
A Breakthrough After Decades
The case was reopened multiple times over the years, most recently in 2021 when the Davie Police Department’s Cold Case Unit began re-examining physical evidence using modern DNA technology. Hair samples recovered from Decker’s clothing were submitted for testing, which revealed a male DNA profile. Investigators then worked with genetic genealogists to trace the DNA back to possible relatives. The search led them to Donald Lawless, a man who lived in Davie during the 1980s and had a long criminal history. Lawless had died in Ohio in 1995 and was cremated, which made obtaining a direct DNA sample impossible. Detectives instead reached out to surviving relatives and obtained a comparison sample from a close family member. The results confirmed that the DNA from the crime scene matched Lawless’s genetic line, conclusively linking him to Decker’s murder.
Posthumous Justice
Although Lawless is deceased, the Broward County State Attorney’s Office formally closed the case, citing sufficient evidence that he was responsible for the crime. Davie detectives believe Lawless may have been involved in additional unsolved murders in South Florida from the same period. Several of those cases also involved women found in canals who had been stabbed or strangled. Detective Eddy Velazquez of the Davie Police Department said during a press conference, “We found out that areas like Fort Lauderdale had similar cases, so there’s no doubt that Lawless has some ties to other cases.”
The Family’s Reaction
For Decker’s family, the identification brought a mix of relief and heartache. Her sister, Gail Demore, said, “To find this out, I mean it’s good, but unfortunately he didn’t pay for his sins.” Demore described her sister as strong-willed and independent. “She was the youngest of three girls. She wouldn’t let anyone take advantage of her. She would fight back,” she said.
A Message for South Florida
The resolution of the case underscores the growing impact of forensic genealogy in solving long-dormant crimes. By combining preserved evidence with cutting-edge technology, investigators were able to identify a killer nearly forty years after the crime. It also highlights the determination of local law enforcement to bring closure to families, even when justice comes decades later. Davie police continue to review other cold cases for possible links to Lawless. For many families across South Florida, the Decker investigation serves as a reminder that no case is ever truly forgotten — and that science continues to close the gap between tragedy and truth.
