By Joe Holden

PHILADELPHIA (CBS) — For the past 18 years, the man known as the “Fairmount Park Rapist” has haunted Philadelphia residents and frustrated police detectives. In this week’s CBS3 Mysteries, a breakthrough could shed new light on the case.

On April 30, 2003, a woman was attacked at Fountain Green and Kelly Drive.

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“He’s absolutely an apex predator,” Philadelphia Police Capt. Mark Burgmann said.

It was the first documented time the man known as the “Fairmount Park Rapist” would strike.

“In this case, there is no closure, he is still out there,” Burgmann said. “This guy’s still out there.”

In July 2003, medical student Rebecca Park was raped and strangled to death in dense woods along Conshohocken Avenue. Park had been out jogging.

“This wasn’t 5 o’clock in the morning, where it’s dark. This was in the middle of the day when this guy was out prowling the parks,” Sheriff Michael Chitwood said.

Eighteen years ago, in Volusia County, Florida, Chitwood was working in Southwest Detectives. He was one of the leader investigators when Park was first reported missing.

“This young lady, serving our country, fourth-year medical student, her whole life ahead of her and this scumbag, he just snuffed it out,” Chitwood said.

DNA linked the deadly crime to the rape case that happened a few months earlier in April. This time, the Fairmount Park Rapist had escalated to a new level that left practically an entire city terrified and on edge.

October 2003 and another rape happened in the park. Detectives believe it was the same man, but DNA was inconclusive.

The Fairmount Park Rapist would go dormant.

And then in 2007, a fourth woman was raped at knifepoint near Pennypack Park. Once again, DNA linked the case to the ones in April and July 2003. Police recall his chilling words to his victims.

“He said they shouldn’t come out here late at night, why are you out here by yourself, almost like protective at that point, almost as if it was a date,” Burgmann said. “Pretty sick. Very sick individual, well there are four women here, one that he killed.”

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Last month, new information and details were released by Philadelphia Police in hopes to revive the case. For the first time, police said the rapist was known to hold his knife in his left hand and that he wore an earring in his left ear.

Why release those previously undisclosed pieces of information?

“Eighteen years. Eighteen years, you figure what do we have to lose at this point, it’s been 18 years,” Burgmann said. “Maybe it’ll jog somebody’s memory or recollection. I think it’s well worth it to do.”

Investigators also have a new composite sketch to help them. A forensic artist used age progression to match how the rapist is believed to look today.

“This is one of the cases that is just pending, and it’s just been the back of everybody’s mind,” Ryan Gallagher said.

Gallagher is a forensic laboratory manager for the police department.

Scientists were able to lift away specific details from the rapist’s DNA. They developed this image.

(Credit: Philadelphia Police Department)

“This type of DNA uses your DNA as a blueprint to kind of build what your features are, build what your face looks like, and DNA codes for things like hair color, eye color, freckling, skin color,” Gallagher said.

Advances in science have also helped police tie the Fairmount Park Rapist to a specific family tree through genealogical mapping. That means police have identified members of his family, but so far, there has been no definitive breakthrough on who he is.

Even with the passage of time, to this day, there have been no hits on his DNA in national or global databases.

“There’s a lot of theories on what happened to the guy, did he stop committing crimes, did he move out of the country, is he deceased? We don’t know,” Burgmann said.

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Constant advances in technology bring investigators only closer to answers and yet, they acknowledge the hunt for justice has been painfully slow.