premise: Passenger Garnet Caton said the victim was sleeping with headphones on before he was stabbed 40 or 50 times by the man sitting next to him . " We heard this bloodcurdling scream and turned around , and the guy was standing up , stabbing this guy repeatedly , like 40 or 50 times , " Caton said from a hotel in Brandon , Manitoba , where he and other passengers had been taken to rest . Caton said the bus stopped and the passengers scrambled to disembark while the suspect allegedly began methodically carving up the man 's body . The attacker severed the man 's head with a large hunting knife and held the head up by the door for others to see . What 's a possible reason the man stabbed the victim ?
hypothesis: Because a passenger was watching .