Ancestry site leads to arrest of alleged Tampa Bay serial rapist 21 years later

PINELLAS COUNTY, Fla. — A man suspected of multiple rapes in the Tampa Bay area dating back to 1998 was arrested thanks to innovative DNA technology.

The Pinellas County Sheriff’s Office and Venice Police Department collaborated in the investigation and arrest of Robert Thomas, 61, in Niles, Michigan.

Thomas is suspected of raping a woman in Pinellas County in 1998 and another woman in Venice in 1999. It took detectives two decades to track him down and bring closure for the victims in this cold case.

On Oct. 9, 1998, deputies responded to a sexual battery call at Indian Rocks Beach. A 21-year-old woman was reportedly walking alone on the beach when she was approached by an unknown naked man who asked for a cigarette. The man chased her down and raped her, the sheriff’s office said.

The suspect forced the woman to clean herself off in beach water, but his DNA was still later found on her and stored by the Florida Department of Law Enforcement.

The FDLE Crime Lab created a DNA profile for the suspect and the search began.

In May 1999, FDLE matched the DNA from the Indian Rocks Beach rape to DNA left in a rape victim in Venice. In this instance, the suspect broke into a home and raped a woman.

Detectives now had a match in two cases, and but still no suspect to match it to. For the next 20 years, police continued hunt the rape suspect down.

Along the way, detectives identified 90 possible suspects, but all 90 were excused. By Feb. 2018, detectives were still at square one.

In October 2018, FDLE introduced a new genetic genealogy mapping technique using a site called GEDMatch. Similar to sites like, GEDMatch is available to the public, and more importantly, law enforcement.

When people purchase their DNA results from a site like, they have the voluntary option to load their profile onto GEDMatch to see if they can find more distant relatives that may not be using the same platform like

The DNA had a distant match to a GEDMatch user in Ocala, Florida. According to Pinellas Sheriff Bob Gualtieri, the woman shared an ancestor at the great-great-grandparent level with the suspect. She was cooperative with detectives who met at her house and worked tirelessly to map out her family tree.

Detectives eventually identified Robert Thomas as the suspect and a perfect match to the DNA logged in the 1998 and 1999 rape cases. He was found living in Niles, Michigan and was arrested Dec. 12 on armed sexual battery charges.

“His general statements were that he had been here in Pinellas County around that time,” Gualtieri said. “He was working as a contractor. He was around here, but he wouldn’t make any admissions. Again, once he was directly confronted he shut right down.”

Thomas had already been arrested at a federal level in 2010, but Gualtieri said a processing error caused the DNA to not be collected properly in booking. The cold case could have been closed in 2010 if that error had not been made, Gualtieri said.

Gualtieri added that Pinellas detectives were in close contact with the rape victim from Indian Rocks Beach.

“It’s something that you never get over,” the sheriff said. “It’s something that you live with, and as a victim of a crime you certainly want to see justice and see someone punished for what they did.”