Forty-one years after the remains of a 16-year-old girl were discovered on a Florida property, police have identified the victim using DNA technology.

The Hernando County Sheriff’s Office announced on July 20 that they positively identified the remains of Theresa Caroline Fillingim, who went missing while on vacation on May 16, 1980. Fillingim's sister had reported her missing to the Tampa Police Department.

Fillingim’s remains were recovered from serial killer Billy Mansfield Jr.'s property on April 3, 1981. Deputies uncovered Fillingim’s body alongside the remains of the bodies of three other women on Mansfield's property.

Mansfield is currently serving a life sentence in California.

For years, Fillingim’s body remained unidentified alongside that of another woman, partly because of difficulties investigators faced with determining her identity. There was a break in the case in 2020 when a lab at the University of North Texas developed a complete DNA sample from a sample of the remains submitted by the sheriff's office. However, no match for the body was found when it was entered into a national database.

But this changed earlier this year when the sheriff's office sent another sample to the Virginia-based DNA technology company Parabon Labs. Using Parabon's "Snapshot DNA Phenotyping'' technology, which produces a description of a victim based on traits like skin color, eye color and ancestry as opposed to a genetic match, investigators were able to create a victim profile.

With the new profile in hand, Fillingim’s remains were at long last positively identified together with a sample of her sister’s DNA.

In December 1980, Mansfield was arrested together with his brother after the half-naked body of 29-year-old Rene Saling was found in a drainage ditch at the side in Watsonville, California.

He was indicted by a Hernando County grand jury in 1982 and ordered to stand trial. After two weeks, Mansfield accepted a plea bargain and a 25-years-to-life sentence, and admitted to killing Fillingim and the three other women discovered on his property.

This is the second time in recent weeks where Parabon’s technology has helped detectives crack open a cold case. Last week, detectives in Pennsylvania arrested 68-year-old David Sinpoli for the murder of 19-year-old Lindy Sue Biechler in 1975. After Parabon identified him as a person of interest in her case, police were able to link Sinpoli through DNA testing.