When being held prisoner, keep watching the patrolling guard. After a short time, he will bolt for the bathroom and an FMV sequence will start. After it ends, lay down and crawl under the bed. The guard will cannot see you, and will enter the cell thinking you escaped. Crawl out (you might get shot once in doing this), use the ketchup to heal, and choke out the guard. You are now free and will find your equipment nearby. Note: Reveler Ocelot planned on you escaping, and put a bomb in your equipment. Search through your things, find it, and throw it away.