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Break in 'Pillowcase Rapist' case came from DNA of suspect's son

The breakthrough in the decades-old serial rape case was due to familial DNA, Florida prosecutors said.

A man charged with two counts of sexual battery has been connected to a string of sexual assaults that began nearly 40 years ago in the South Florida area, prosecutors said Thursday.

Robert Koehler, 60, has been identified as a suspect in as many as 25 attacks allegedly committed by a man authorities dubbed the "Pillowcase Rapist," Miami-Dade State Attorney Katherine Fernandez Rundle told reporters at a press conference.

Koehler was arrested Saturday in Palm Bay in connection to a 1983 armed sexual battery case out of Miami-Dade County based on a DNA match, according to court and jail records.

"The DNA also matches additional DNA samples left behind by the individual who became known as the Pillowcase Rapist," Rundle said.

Robert Koehler.Miami Dade Corrections

The so-called "Pillowcase Rapist" was connected to up to 40 cases in which the suspect would cover victims' faces during the sexual assaults. Rundle said that the suspected serial rapist terrorized women in Florida between 1981 and 1986 from Miami to Deerfield Beach.

"The key break in the case came when Koehler’s son was arrested last year in a felony domestic violence, and his DNA provided a close familial match for the unknown rapist," the state attorney said.

The 60-year-old was already on the state's sex offender registry after a 1991 sexual battery conviction. But Rundle said that his DNA was not in the FBI's Combined DNA Index System, or CODIS, because his case occurred before collection of DNA was required in such felony cases.

Though police knew through rape kit collection that the "Pillowcase Rapist" was the same suspect in a string of assaults, they could not identify the person through the existing resources, the prosecutor said.

Rundle's office and local police made a joint request to the Florida Department of Law Enforcement to do familial DNA searches on DNA profiles similar to the rape kit evidence, which matched with Koehler's son after his arrest last year.

"And FDLE determined the DNA of the son was so similar to the DNA of the then-unknown offender, that the offender had to be the man’s father," Rundle said.

A warrant issued by a judge following Koehler's Saturday arrest confirmed "100 percent" that he was the suspect who left behind his DNA in many of the "Pillowcase Rapist" cases, Rundle said. She said her office plans on pursuing charges against Koehler in many of the rape cold cases.

"Via DNA, we will work to be able to file those cases only where the victims are still available, where the DNA is sufficient and admissible," Rundle said.

A judge ordered Koehler be held without bond on the two sexual battery charges in the 1983 case. He has not entered a plea and t's unclear if he has an attorney.