• Jury convicts Robert Koehler in 1984 sexual assault after decades-long cold case investigation
• DNA from son’s 2020 arrest led detectives to suspect in South Florida rape series
• Prosecutors link Koehler’s DNA to at least 25 attacks spanning 1981 to 1986

MIAMI, Fla. (TDR) — A man suspected of terrorizing South Florida women in a series of rapes during the 1980s was convicted Nov. 3 in one of the attacks, bringing closure to a cold case that haunted the region for decades.

Miami-Dade County jurors found Robert Eugene Koehler, 66, guilty of sexual battery, kidnapping and burglary after deliberating for less than two hours. The convicted sex offender, known as the “Pillowcase Rapist,” faces sentencing Nov. 24.

The conviction stems from a 1984 attack on a 22-year-old woman in her southwest Miami-Dade County townhouse. The victim testified that Koehler broke into her home, held a knife to her neck, threatened to kill her and covered her face with fabric before assaulting her.

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DNA breakthrough cracks decades-old case

The case remained unsolved for nearly four decades until a DNA breakthrough in 2020 led investigators to Koehler. Authorities obtained a DNA sample from Koehler’s son following an unrelated arrest. When the son’s DNA was entered into the FBI’s Combined DNA Index System, known as CODIS, it matched evidence from the 1983 rape case closely enough to indicate the attacker was likely his father.

Detectives conducted surveillance on Koehler in Palm Bay, where he worked as an electrician, and collected DNA samples from objects he touched, including a shopping cart handle and a door. Laboratory analysis confirmed the match, and authorities arrested Koehler on Jan. 22, 2020. He has been held without bond since his arrest.

Joanne Hsu, director of the Surveys of Consumers at the University of Michigan, noted the significance of modern forensic technology. Prosecutors told jurors the odds of someone other than Koehler being the source of the DNA was nearly 90 billion to one, later refined through additional testing to 16.55 octillion to one.

Pattern of terror across South Florida

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Authorities say the “Pillowcase Rapist” earned his moniker by using pillowcases or other fabrics to cover his victims’ faces, or sometimes his own, during the attacks. The assailant would break into homes at night, assault women, tie them up and steal from their residences.

Miami-Dade State Attorney Katherine Fernandez Rundle said prosecutors have connected Koehler’s DNA to at least 25 sexual assaults in Miami-Dade County alone between 1981 and 1986. However, investigators believe there may have been more than 40 victims overall across South Florida, from South Miami to Deerfield Beach.

The attacks attracted extensive media attention in the 1980s, and authorities created a task force to investigate. However, the trail went cold for decades as DNA technology at the time was limited to basic blood typing.

Previous conviction and ongoing cases

This marks Koehler’s second conviction related to the “Pillowcase Rapist” cases. In March 2023, he was sentenced to 17 years in prison for raping a 25-year-old woman in 1983. Additional charges remain pending in both Miami-Dade and Broward counties.

Broward County Sheriff’s Office Cold Case Unit detectives charged Koehler in six separate sexual assault cases in 2022, describing the attacks as carried out with “diabolical precision.” Those cases will proceed after the Miami-Dade proceedings conclude.

During the trial, Koehler took the stand and offered what observers described as a bizarre defense, claiming he was kidnapped, drugged and tortured by corrupt police officers who planted his DNA at crime scenes. The jury rejected his testimony.

Victim courage praised

Fernandez Rundle praised the victim’s courage in a statement following the verdict. “Today’s jury verdict finding Robert Koehler guilty of sexual battery, kidnapping and burglary finally closes the book on a terror that gripped the women of South Florida for far, far too long,” she said.

The state attorney credited two generations of police officers and forensic scientists whose work led to the conviction. She particularly commended prosecutor Laura Adams for her efforts in securing the guilty verdict.

Koehler, sitting in a wheelchair during the verdict reading, showed no emotion as the court clerk announced the jury’s decision. Miami-Dade County Circuit Judge David Young presided over the four-day trial.

Records show Koehler was previously convicted of sexual battery in Palm Beach County in 1990 and sentenced to probation, which he later violated. He served 120 days in jail but that case was never linked to the South Florida assault series until recent DNA analysis connected the crimes.

How many other cold cases could be solved with advances in DNA technology and familial matching?

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