A murder case spanning 40 years was closed July 18 when an arrest was made in the murder of Linday Sue Biechler based on DNA evidence found on a coffee cup discarded by the suspect at Philadelphia International Airport, writes Eduardo Medina for The New York Times.

Biechler, a recently-married 19-year-old flower shop clerk, was stabbed 19 times at her Manor Township, PA apartment in 1975. The identity of the killer went unknown for 46 years.

On July 18, David Sinopoli, 68, of Lancaster County was arrested on homicide charges.

“This has been a never-ending pursuit of justice for Lindy Sue Biechler,” Heather Adams, the district attorney in Lancaster County, said.

In 2000, investigators gave a DNA sample from the crime scene to Cece Moore, a genetic genealogist.

Through the sample and other research, Moore was able to narrow the list of suspects, including Sinopoli, to those whose ancestors had lived in Gasperina, Italy.

Sinopoli had also lived at the same apartment building as Ms. Biechler.

In February, authorities followed Sinopoli into Philadelphia International Airport. They took his DNA from a coffee cup he had thrown in the trash before boarding a flight.

It matched samples collected from Ms. Biechler’s underwear.

Read more at The New York Times about this cold case arrest.

Here’s an ABC News report on the arrest.