I thought standard FBI secret police caliber was 10mm or .40 S&W these days? Purely coincidentally, of course. There's no reason to believe the US Stasi would have anything at all to do with something so minor as a prisoner committing suicide. In a cell under 24-hour video surveillance.
In the aftermath of the Miami shootout in 1986 where two Feebs were killed and another five wounded (largely because they were outgunned by the two cretins they tried to arrest), the Feebs decided they needed a stronger cartridge and went with the 10mm.
Field tests proved they couldn't handle the recoil.
So they necked the 10mm cartridge down a little and the .40 S&W was born.