JonBenét Ramsey's Brother Reveals Clue That Could Finally Solve Her Murder

JonBenét Ramsey's brother says the key to solving her nearly 30-year-old murder mystery has been there all along ... and he's begging investigators to take another look.

Burke Ramsey, who was just 9 when his younger sister was killed in Colorado, broke his decade-long public silence in an interview with the Daily Mail ... insisting DNA evidence found on JonBenét could finally crack the case.

"We need to find that match. It's the best evidence we have," Burke said ... pointing to unidentified DNA recovered from beneath JonBenét's fingernails.

He wants investigators to send the samples to different labs for more testing ... saying, "Find the match. That will go a long way to bringing justice. It's been 30 years and enough is enough."

Burke also pushed back against years of suspicion surrounding his family ... declaring, "I didn't do it," and insisting the DNA evidence points away from the Ramseys.

As you know ... 6-year-old JonBenét was found strangled in the basement of her family's Boulder, Colorado home on December 26, 1996. Her murder remains unsolved.

The case is back in the spotlight, with Diane Sawyer revisiting the murder in a new ABC special Friday ... while Melissa McCarthy is set to play JonBenét's mom, Patsy Ramsey, in an upcoming Netflix drama.

As TMZ previously reported ... McCarthy hopes the series sparks a fresh investigation, and she's said she doesn't believe anyone in the Ramsey family was responsible.

Burke, meanwhile, says he's willing to help investigators however he can.