Frank Thies was convicted after investigators used genetic genealogy to revisit a cold case that had been unsolved for decades.
PROVIDENCE, RI — An Indiana man was sentenced Tuesday to two consecutive life prison terms for sexually assaulting two girls at knifepoint in the woods of Exeter nearly four decades ago.
Superior Court Justice Sarah Taft-Carter sentenced Frank Thies, 70, in Washington County Superior Court after a jury found him guilty in December of first-degree child molestation and first-degree sexual assault. The sentence sends Thies to the Adult Correctional Institutions in Cranston and closes a case that Rhode Island investigators said was revived by advances in genetic genealogy.
Prosecutors said the attacks happened April 12, 1987, in a wooded area of Exeter. The two victims, both younger than 14 at the time, did not know the man who assaulted them, according to state officials. Attorney General Peter F. Neronha said the case reached sentencing because of the victims’ “tireless bravery” during the original investigation and in the years that followed. Neronha said genetic genealogy allowed the state to hold Thies accountable after the case sat unsolved for decades. Taft-Carter also issued a no-contact order barring Thies from contacting the victims.
The case was built from evidence collected in 1987 and preserved through the long investigation. Police said the girls, ages 11 and 13, were attacked in the woods off Stony Lane. DNA from clothing was collected, but investigators did not identify a suspect at the time. Rhode Island State Police reopened the case in 2019, more than 30 years after the assaults. Investigators later worked with forensic genealogy specialists, who used DNA evidence to narrow the search for the suspect. Officials said the process pointed to Thies, who had been living in Indiana.
The renewed investigation reached Indiana in 2022, when detectives questioned Thies in Terre Haute. State police said investigators also worked with the Naval Criminal Investigative Service as they reviewed Thies’ military background. Authorities said Thies had served in the U.S. Marines and the U.S. Navy and had reported to the Naval Justice School in Newport around the time of the 1987 attacks. With help from Indiana State Police, investigators obtained DNA from a discarded item and compared it with evidence from the Exeter case. Officials said the test matched Thies to the suspect profile.
Thies was arrested Oct. 19, 2022, in Indiana as a fugitive from justice after a Rhode Island statewide grand jury indicted him. He was later extradited to Rhode Island. The case went to trial in December 2025 at the J. Howard McGrath Judicial Complex in Wakefield. The trial lasted nine days. The victims testified before the jury, and jurors also heard evidence about the DNA testing and the police investigation. On Dec. 11, 2025, the jury convicted Thies of one count of first-degree child molestation and one count of first-degree sexual assault.
During the trial, prosecutors said the evidence proved beyond a reasonable doubt that Thies assaulted the two girls at knifepoint in the Exeter woods. The state did not say in its sentencing announcement whether Thies spoke in court Tuesday. It also did not report any appeal filing by the defense as of the sentencing announcement. Assistant Attorney General Timothy Healy and Special Assistant Attorney General Jessica Villella handled the prosecution. Detective Sergeant Kyle Draper and retired Major Michael Quinn of the Rhode Island State Police led the investigation with support from Indiana authorities.
Colonel Darnell S. Weaver, superintendent of the Rhode Island State Police and director of the Department of Public Safety, said the victims had waited decades for the case to reach an outcome. “We recognize that nothing can undo the harm that was done, but today’s outcome reflects our commitment to justice, no matter how much time has passed,” Weaver said. The case became one of Rhode Island’s older cold cases to move from DNA review to conviction and sentencing, a process investigators said depended on preserved evidence, genealogy work and cooperation across state lines.
Thies is now serving two consecutive life sentences at the Adult Correctional Institutions. The next public milestone would be any post-sentencing court filing or appeal, but no such step had been announced by state officials as of Thursday.
Author note: Last updated June 18, 2026.