I doubt this happened in this Senter case, but Pittsburgh Underboss Chucky Porter was let out after -10 years of a 27 year sentence after cooperating with feds from prison to stop 6 murders, including of some people who testified against him and turning the feds into the Pgh Mob- San Diego Casino skim.

He could not be used to testify against anyone because he perjured himself while testifying in his own defense.
But he definitely helped the Feds stop murders of informants including some in the witness protection program.

He gave information here and there over a decade.

So guys can hear information from other guys in prison and pass the information along and build up a resume to help get them an early release.

But I doubt it took 30 years of helping Feds to get him out, unless it did due to the high number of murders.