Kevin Spacey’s alleged first accuser, branding him a sexual predator, has been found dead.

The first whistleblower to go public with allegations branding shameless Kevin Spacey a sexual predator is dead — and her grieving family is demanding answers!

Now, in a world exclusive, RadarOnline.com can reveal investigators have launched a murder probe into Linda Culkin’s mysterious death, while 59-year-old Spacey faces a felony charge of indecent assault and battery for allegedly groping a young man in Nantucket, Mass., in 2016.

On Feb. 25, Culkin was walking to her home when she was mowed down by a Toyota as she stepped into a busy intersection, Quincy Police Capt. John Dougan told Radar. She later died at Boston Medical Center.

“Linda was one of the first to accuse Kevin Spacey of attacking young men, and I find it very odd that you don’t hear anything more about her accident — or about the person who hit her,” said Culkin’s cousin Cindy, 60. “It’s like it happened, and now there is nothing!”

Culkin, a nursing assistant with mental problems, began cyberstalking and terrorizing Spacey and his team in 2009 after one of her young male patients told her the details of an alleged attack by the American Beauty actor.

In 2014, she was sentenced to 51 months behind bars after pleading guilty in federal court to sending harassing emails, making fake bomb threats and mailing an envelope containing white powder to Spacey’s associates.

But four years later, Spacey’s career went up in smoke after actor Anthony Rapp broke decades of silence to charge that the actor tried to molest him at age 14.