Fr. John Gerard, S.J. found in the Marshalsea Prison a servant of the Jesuit Father Edmund Campion, who had been arrested "on account of some words he had let fall in praise of" Campion.
" On my arrival there I saw him laden with heavy fetters on his legs, besides which he wore a very rough hair-shirt. He was most lowly and meek, and full of charity. I happened one day to see a turnkey strike him repeatedly without the servant of God uttering a single word. He was at length taken with three others to the filthy Bridewell. One of their number died of starvation a few days after their transfer."Gerard obtained leave one day, on his way from court to prison, to visit some friends, pledging himself to return to the Marshalsea that night. He employed his liberty in visiting this humble confessor in Bridewell. " He was lying ill, being worn out with want of food and labor on the tread-wheel. It was a shocking sight. He was reduced to skin and bone, and covered with lice that swarmed upon him like ants on a mole-hill; so that I never remember to have seen the like."
Link (here) to the mentioned portion of the essay entitled, A Jesuit In Disguise.