BALTIMORE (WJZ) — Could a nearly 50-year-old secret be behind the murders of several Baltimore teenagers?

WJZ continues its investigation into the murder of young nun Sister Cathy, who was silenced right before she was about to blow the whistle on a powerful sex ring run by priests and police.

WJZ has learned that police are now looking into whether other unsolved murders could be connected.

Sister Cathy Cesnik’s decomposing body was found frozen in a ditch in Lansdowne in January 1970.

The murder of this popular nun has never been solved, and neither have the murders of five young people killed over the next decade.

Now, Baltimore County police are actively trying to determine whether the cases are linked.

In a rare interview, the aunt and sister of Heather Porter talk about the most painful time of their lives.

In 1981, 13-year-old Heather’s body was found in a wooded area in Towson.

She’d been raped and killed.

“It was the beginning of the worst nightmare that I wouldn’t wish on nobody,” said Porter’s aunt, Sarina McCloud.

“She had two thumbprints on her neck, she had a handprint on her arm or bruises,” said Mary Porter, Heather’s sister. “She had skin underneath her fingernails. Her fingernails were broke from the struggle. So she fought to the death.”

So did another teenager brutally murdered during this same time.

14-year-old Danny Crocetti, an altar boy, went missing in March of 1975.

Days later, two boys discovered his body.

“Danny was found in a stream, stabbed in the throat, behind a Catholic school,” said one of Crocetti’s classmates, Michele Cosden.

He had puncture wounds on his hands from trying to defend himself.

Police led his shaken father and uncle to the gruesome scene.

Danny’s classmate, Cosden, is seeing this decades-old murder with new eyes.

“This is a cold case, and maybe it shouldn’t be. Maybe there’s a connection,” she said.

One of WJZ’s sources is convinced that these murders have too many similarities to be a coincidence.

[Reporter: “The first time you heard that Heather’s murder might be linked to other murders, in the same area, in the same time period, do you remember how you felt?”]

“I felt hope. Oh my God, am I going to have some peace?,” Mary Porter said.

Were Heather, Danny, and Sister Cathy silenced by members of a powerful sex ring run by priests and police?

WJZ’s year-long investigation reveals that during the time of the murders, there was a well-hidden culture of sex abuse at Catholic schools and churches.

Many women who’ve shared their stories of abuse with WJZ say victims confided in Sister Cathy right before she was murdered.

All these years later, Baltimore County police still believe someone out there has information that could solve these cases.

“We’ll continue to try to look for any leads, any additional evidence that we can find,” said Corporal Shawn Vinson, with the Baltimore County Police Department.

“They have semen, they have skin, they have hair, they have a piece of shirt, and I don’t understand because this is 2017. With all today’s technology, nothing,” Mary Porter said.

[Reporter: “What if the person who murdered your sister is dead?”]

“If you can prove that they did it, I’ve got justice,” Porter said. “At least they’re dead. At least they can’t do it to anyone else. They can’t do it to another living soul. They can’t break another family. They can’t hurt another innocent child.”

Baltimore County police say no tip is too small, and anyone with information on this case should call (410)887-2214

Follow @CBSBaltimore on Twitter and like WJZ-TV | CBS Baltimore on Facebook