BETHLEHEM, Pa. — For 47 years, Holly Branagan has been at rest at Holy Saviour Cemetery in Bethlehem.

Every once in a while, someone visits her grave and leaves a memento.

March 1979, The Freedom High School senior was stabbed to death in her Pine Top Trail Bethlehem home.

The case went cold until a grand jury investigation in 2014.

“We do have a suspect and don’t have the ability to press charges. Circumstantial evidence can be strong in a case. To file charges, we need to reach a level of probable cause,” said Former Bethlehem Police Detective Thomas Galloway in a 2018 interview with 69 News.

Back then, investigators told 69 News that suspect was an acquaintance of the family.

Now, they’re hoping to get solid answers by partnering with the Cold Case Foundation, following new leads and re-submitting evidence for DNA testing using a new method called “MVAC.”

“MVAC uses a sterile solution in a vacuum to collect the biological material from the surface, so it can potentially recover DNA that traditional methods before might not have been able to,” said Bethlehem Police Cpt. William Audelo.

There are several challenges facing investigators: The passage of time, a crime scene that wasn’t preserved by modern standards, and the reality that just because someone’s DNA is found, doesn’t mean they committed a crime.

“Our job now is to determine whose DNA may be represented, how it might have gotten there, and most importantly, whether or not it has relevance to Holly’s murder,” said Audelo.

Investigators say they hope that information will bring closure to those who have mourned Holly and lived with the mystery surrounding her death.

Anyone with information on Holly Branagan’s murder is asked to call Bethlehem Police.