Over the years there has been speculation about who killed JonBenét Ramsey in 1996.

The list of possible suspects in one of the highest-profile murder cases of all time – when the six-year-old beauty pageant contestant was found dead in the basement of her family’s home in Boulder, Colorado on Christmas morning – is long.

The list includes everyone from her parents John and Patsy Ramsey to her then nine-year-old brother Burke to convicted pedophile Gary Oliva and former teacher John Mark Karr, who confessed to killing her in 2006 but was never charged in connection with her Death.

But a potential suspect catches her eye, at least to her father: a masked intruder who sneaked into the home of a 12-year-old girl in Boulder, Colorado, nine months after JonBenét’s murder. The suspect raped the girl and then ran away when the child’s mother scared him away.

“For me, it could have easily been the same person,” Ramsey tells PEOPLE in an exclusive interview.

But John adds: “The police dismissed it and said, ‘No, it’s not the same.'”

John opens up exclusively to PEOPLE ahead of the upcoming Netflix docuseries Cold Case: Who Killed JonBenét Ramsey?, Streaming Monday, November 25th.

The three-part series takes a new look at the murder case that began when John found his young daughter dead in a dusty basement room in their posh neighborhood.

John and his late wife Patsy also found a threatening handwritten ransom note in their home, believed to have been left by the killer.

But the parents of the deceased girl quickly became suspects in the sexual assault and murder of their daughter, who died from strangulation and a blow to the skull.

The three-part Netflix documentary delves into the authorities’ missteps made by John while investigating JonBenét’s murder amid an international media frenzy that only made things worse.

He says he is speaking out in part to encourage someone to come forward with new information and to “put pressure” on police to use advances in DNA technology and genetic genealogy to finally catch JonBenet’s killer.

To learn more about John Ramsey’s fight to ensure JonBenéts’ murder is solved while he’s still alive, subscribe to PEOPLE now or pick up the new issue of People on newsstands next week.

Speaking to PEOPLE, John expressed his shock when he learned that the unidentified 12-year-old girl had allegedly been raped in the middle of the night two miles from where the Ramseys lived — and that she had gone to the same dance studio as JonBenét .

“I think the approach was exactly the same,” he tells PEOPLE. “I think the killer was in the house when we got home and waited until we went to sleep.”

In the case of the 12-year-old girl and her family, “they came home, turned on the alarm and the killer was already in the house. A very similar method, and yet the police screwed it up. “It was the same investigator as in our case,” says John.

“But even the little girl’s father said, ‘On a scale of one to ten, I rate the police at minus five.’ They’re just… just stupid ignorance. But yeah, I think it was most likely the same person.”

John, Patricia and Burke were never charged in connection with JonBenét’s murder. Patsy died in 2006.

The three-part Netflix documentaries Cold Case: Who Killed JonBenét Ramsey? begins Streaming Monday, November 25th.