It's hard to understand how the bugs killed him. His cause of death is something else, the bugs just feasted on his decaying body...
First person reference, I've been in many a filthy cell, filthy jail, etc. The levels of disgusting can be obscene. I've seen it and had to live in it. Been in jails with bedbug infestations, roach infestations, spider infestations, rat infestations, and was once in jail with a snake on the loose...
So I've been in these conditions. The dirtiest if the cell may have caused his death, he may have been inhaling or digesting some filthy shyt that killed him. Insects didn't kill him, though. They just started eating his dead body...