A knife-wielding, overweight sex offender dropped dead while raping a 77-year-old Texan woman. Isabel Chavelo Gutierrez broke off his attack to complain he wasn't feeling well—then keeled over. The victim ran from the house, and by the time police arrived, Gutierrez, 53, was dead. Investigators believe he died of a heart attack. He had ridden two miles by bike to reach the home of his victim, whom he had apparently picked out the previous day at a local post office, reports the Corpus Christi Caller. He was on parole at the time of the attack for crimes including the sex assault of a 7-year-old child. (More crime stories.)