jump on a case
v. phr.— «This kind of convoluted back-and-forth is common in prison; inmates do communicate, even when they are not supposed to. And it’s fairly routine for inmates to turn over—and sometimes even invent—damning material in hopes of getting some kind of deal. The risk of other inmates “jumping on a case,” as it is known in prison parlance, is particularly great in high-profile ones like the Fort Dix case.» —“Playing Tricks with the Fort Dix Six?” by Amanda Ripley in Washington, D.C. Time Jan. 14, 2008. (source: Double-Tongued Dictionary)