JonBenet Ramsey's older brother just followed through on his promise to sue CBS for insinuating he killed his sister ... and he's gunning for $750 million.
Burke Ramsey just filed suit against the TV network for its special about JonBenet earlier this fall, where some experts openly theorized that Burke had taken a flashlight to his little sister's head.
He's reportedly asking for $250 mil in compensatory damages and $500 mil in punitive damages.
You'll recall ... Burke already sued one of the experts CBS used on their special, Dr. Werner Spitz, for $150 million ... to which Spitz responded by saying he should be allowed to speculate about who killed JonBenet.
Burke's attorney at the time, L. Lin Wood, previously told us he was planning to sue CBS on his client's behalf. It's unclear if he's repping Burke for this suit.
CBS had no comment.