Gruesome murder on Greyhound bus

The bus was disabled, no way he could have gotten anywhere. This is second degree murder.. the guy is showing no emotions. He does have a family, a stable job, all that but yet no motif.. they have to investigate further into this. What happened at his job interview? Why this kid of all people to kill? Did his wife know he would do this? (She did speak to him prior to this event)