A Colorado father claims Boulder cops may have missed an opportunity to catch JonBenet Ramsey’s killer — by ignoring an attack on his own young daughter which happened months after the infamous murder.

The dad claims a masked man dressed in black broke into his home on Sept. 14, 1997, snuck into his then-12-year-old’s daughter’s room, threatened and raped her.

The terrifying incident was foiled only because the girl’s mother heard voices, and came into the room to investigate, prompting the mysterious man to flee.

JonBenet, just 6, had been killed nearly nine months earlier. She lived less than two miles away, and the two girls went to the same dance studio, the father said.

In a chilling interview with The U.S. Sun, the dad recalled how the same type of cigarette butts — Camel Blue — were found outside both homes and said he begged local police to investigate.

But Boulder cops weren’t interested, he charged. Neither case has been solved.

The girl is only identified by The Sun with the pseudonym “Amy.”

“There are so many similarities between the two cases that I think there’s a very good chance it was the same person,” Amy’s dad told the outlet.

“The only difference is my daughter survived,” he added.

Boulder police were “dismissive” and “disinterested,” the dad alleged.

“They were completely uninterested,” he claimed. “They didn’t care about this at all … they would just lie, telling us they’d look into this or that — but they hadn’t.

JonBenet Ramsey, a child beauty queen, was found dead in her family’s home on Dec. 26, 1996. Authorities said earlier this month they would launch a new probe into her killing with cold case investigators.

Amy awoke to see the stranger standing over her bed. He kept calling her name.

“I know who you are,” he repeated, before warning, “I’ll knock you out, shut up.”

He then sexually attacked her, her father recounted.

The dad hired a private investigator, who discovered the cigarette butts and found other possible links between the two cases — including nearly two dozen burglaries or trespassing reports in the area and background checks which showed possible suspects in Amy’s case once worked in JonBenet’s home — but police allegedly took no action.

“They were completely uninterested … they didn’t care about my daughter’s case and they didn’t even really care about the Ramsey case either,” he said.