DAVIE, Fla. (WFLA) — Nearly 40 years after a woman was murdered and abandoned in a Florida canal, police have identified her killer. The deceased was a man with an extensive criminal history.
Marilyn Decker was 28 years old when Davie police found her floating in the canal off Flamingo Road in October 1987. Detectives said it was clear Decker was murdered. She had multiple stab wounds, and the coroner later confirmed her cause of death was asphyxia.
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Police collected several items from Decker, including his shirt and towel, and identified several potential suspects, but were unable to conclusively pinpoint his involvement in the crime.
The investigation continued into the mid-1990s, when the Florida Department of Law Enforcement joined Davie police in conducting interviews. However, no new clues were obtained, and the case remained unsolved.
That was until the Davie Police Department’s Cold Case Unit reopened the case in 2021. Police interviewed the suspect, contacted Decker’s family, spoke with previous detectives who worked on the case and even placed a sign on Interstate 595 asking for tips.
The case was also filed with the Vidocq Society in Philadelphia and Astrea Forensics, Inc. in California. Detectives said a genealogist was able to identify the suspect using DNA extracted from hair found on Decker’s shirt and towel.
The hairs all shared the same male DNA, an Ohio man named Donald Lawless.
Investigators determined that Lawless lived in Florida from the early 1980s until 1993. Police said Lawless had an extensive criminal history dating back to the 1940s.
Detectives began searching for Lawless and discovered that he had died in Ohio in 1995 and was cremated. He was about 70 years old when he died and would have been 62 when Decker was killed.
Although the main suspect was no longer present, Davie police were able to locate Lawless’ next of kin and provided a DNA sample. Detectives said it was a match.
Police said a combination of genetic genealogy analysis and circumstantial evidence confirmed that Lawless was the person responsible for Decker’s murder. The Broward County State’s Attorney’s Office agreed there was enough evidence to charge Lawless with Decker’s murder and closed the case.
Davie police said detectives have been in contact with Decker’s family over the years and have told them the case is finally solved.
