SOUTH KINGSTOWN, R.I. (WPRI) — The Indiana man accused of sexually assaulting two teenage girls more than 35 years ago faced a judge Thursday.

Frank Thies, 66, pleaded not guilty to one count of first-degree sexual assault and two counts of first-degree child molestation.

Thies, who served in the U.S. Marines and Navy, was taken into custody last month in connection with the incident, which happened back in April 1987.

The girls, ages 11 and 13, were outside playing tennis in Exeter when Thies first approached them. Detectives believe Thies forced both teenagers into the nearby woods at knifepoint, where he sexually assaulted them.

Detectives scoured the woods for clues and collected DNA evidence, but were unable to locate nor identify the suspect at the time.

It wasn’t until the case was re-opened in 2019 by the Rhode Island State Police’s Special Victims Unit that investigators began closing in on Thies.

Back in August, detectives learned the suspect was likely one of three brothers, all of whom were originally from New York and served in the military.

Detectives later found out that the oldest brother, identified as Thies, had reported to the Naval Justice Academy in Newport the day before the assaults.

With the help of Indiana State Police, several discarded samples of Thies’ DNA were collected and tested to determine whether it matched the DNA collected more than three decades ago.

Those DNA samples were collected from a lottery ticket, beer bottle, soda can and fast food wrappers, according to a police report obtained by 12 News.

Police said Thies was apprehended and charged as a fugitive from justice soon after the results revealed his DNA matched the suspect’s.

Thies was arraigned Thursday and ordered held without bail. His next court date is scheduled for next week.

Meanwhile, detectives are looking into whether Thies was involved in any other sexual assaults that have gone unsolved over the years.

Thies is believed to have previously lived in New York, North Carolina, South Carolina, Florida, Virginia, Mississippi, Tennessee, Washington, D.C., Texas, Italy and the United Kingdom before moving to Indiana.

Anyone who has additional information about Thies is urged to contact the Rhode Island State Police Special Victims Unit at (401) 764-5394.