CSI: NY, Season 7

Jo Danville:
So from about 8:00 to 11:00, I'm just supposed to take your word for it that you were in your room? And the only person who can account for your whereabouts earlier that day is your girlfriend [starts writing down]

Billy Travers:
What are you doing?

Jo Danville:
Math. Because you're not man enough to admit what you did. Now I gotta do Math. I hate Math. Half hour by train to get to your parents' place. 25 minutes to stand outside and build the courage to kill them. Another 40 minutes inside to do the deed and change your clothes. 15 minutes to puke and then find a place to ditch the bloody clothes. Another half hour to travel to your room (she sums up) Five... ten... carry one... two hours and 20 minutes, give or take. Plenty of time for you to commit the murder and get back to your room.