I would be surprised if the releases containing anything especially new, but the government most certainly maintains incriminating information on themselves. For instance we now know that the FBI discovered compromising information on MLK and tried to black mail him into suicide. [1] They also discovered his infidelity through surveillance and contacted his wife again trying to damage his character. This was all well documented and maintained for decades after it had happened. If you want death and murder, there's things like US involvement in Operation Condor [2] which was long speculated but finally fully verified by documents declassified under Clinton. And there are countless other examples.

Releases staggered by decades come with great plausible deniability. Is the FBI today responsible for what the FBI of the past did to MLK? If anything relevant was revealed, I'd expect the modern versions of the involved agencies to be the first condemn those actions. Whether that's genuine or not is practically impossible to know. But it's almost certainly sufficient to ensure they'll never face any meaningful consequences for their actions.

[1] - https://www.eff.org/deeplinks/2014/11/fbis-suicide-letter-dr...

[2] - https://en.wikipedia.org/wiki/Operation_Condor#U.S._involvem...