PHILADELPHIA -- A suspect was arrested this week in a young woman's 1975 murder after a genetic genealogist -- who called the cold case extremely difficult to solve -- turned to a brand new investigative approach.
Lindy Sue Biechler, 19, was stabbed to death at her Manor Township, Pennsylvania, apartment on Dec. 5, 1975, according to the Lancaster County District Attorney's Office. She suffered 19 stab wounds to her neck, chest, back and abdomen, prosecutors said.
Biechler was found lying on her back with a knife sticking out of her neck, prosecutors said, adding that the knife was from Biechler's own kitchen and a tea towel was wrapped around its handle.
Decades went by without an arrest in the gruesome crime.
When DNA analysis emerged in the 1990s, prosecutors said, the investigators submitted DNA from semen left on Biechler's underwear to CODIS, the national law enforcement DNA database, but no match was ever found.
In 2020, CeCe Moore, a former ABC News contributor and the chief genetic genealogist at Parabon NanoLabs, began investigating the case with genetic genealogy, which uses an unknown suspect's DNA to trace his or her family tree.
Genetic genealogy made headlines in 2018 when the novel investigative tool was used to find the Golden State Killer. Genetic genealogy takes an unknown suspect's DNA left at a crime scene and identifies it using family members who voluntarily submit DNA samples to a DNA database; this allows police to create a much larger family tree than if they only used databases like CODIS.
SEE ALSO: How the 'Golden State Killer,' a serial rapist, murderer, evaded capture for decades
As Moore began working on Biechler's case, she was "extremely disappointed" when she uploaded the case file to a DNA database and only could find very, very distant relatives of the unknown suspect.
"Usually I'm able to identify common ancestors. But because the common ancestors between the matches and the suspect in this case were probably back in the 1700s [or] 1600s, I wasn't able to approach it the way that I do most cases," Moore told ABC News.
"It was really tugging at me, so I decided to develop a new approach," she said. "There was a very clear migration pattern from a town in southern Italy called Gasperina, to Lancaster, Pennsylvania."
Moore said she scoured Lancaster documents for months and landed on a local club of residents who were from Italy.
"Those membership cards listed when people were born. Because I knew that this suspect had roots in this small town Gasperina, I went through all of those cards and found the people who had immigrated from Gasperina to Lancaster," Moore said.
She said she learned about 2,300 Italians lived in Lancaster at the time of the crime -- which for her was a "manageable" number.
"About half are gonna be female. A certain percentage are gonna be too old or too young. I knew this person had to be fully Italian from Gasperina or close by," Moore said.
"I worked through each and every one of those families that had migrated from that very specific town," she said. "It was really only possible because of this very unique [membership card] record collection that Lancaster had."
Moore said she compared those membership cards with Ellis Island records and World War I and II draft registration cards to identify the men who moved from Gasperina to Lancaster, and then worked to identify their descendants.
"I just quietly worked on it on my own time. I didn't know if it would work," Moore said.
After looking at all Italian families in Lancaster in 1975, Moore said she zeroed in on 68-year-old David Sinopoli. All of his grandparents were from Gasperina, Moore said, and he had previously lived in Biechler's apartment complex, prosecutors said.
In February 2022, investigators surveilled Sinopoli and recovered a coffee cup he used and threw away at the Philadelphia International Airport, prosecutors said. Labs later confirmed the DNA on Sinopoli's coffee cup matched the DNA from the semen on Biechler's underwear, according to prosecutors.
Investigators also found that DNA in blood left on Biechler's pantyhose was determined to be consistent with the semen from Biechler's underwear, prosecutors said.
Sinopoli, who has lived in Lancaster since the murder, was arrested at his home on Sunday on a charge of criminal homicide, prosecutors announced Monday. His preliminary hearing is set for July 25. No defense attorney is listed.
Sinopoli "was not on our radar," Lancaster County District Attorney Heather Adams said at a news conference. Sinopoli was "never cleared," Adams said, but "none of the tips over the years had suggested him as a possible suspect."
Biechler's murder marked the first time Moore used this new approach, and she said she's since used it successfully in two more cases.
Adams praised Moore and Parabon NanoLabs in a statement, saying the arrest wouldn't have been possible without their help.
"There has been a never-ending pursuit of justice in this case that has led us to identifying and arresting Sinopoli," Adams said. "Certainly, law enforcement never forgot about Lindy Sue, and this arrest marks the first step to obtaining justice for her and holding her killer responsible."