1.70. A man driving his car turns on the radio. He then pulls over to the side of the road and shoots himself. (This is different from #1.71.)
1.70 answer: He worked as a DJ at a radio station. He decided to kill his wife, and so he put on a long record and quickly drove home and killed her, figuring he had a perfect alibi: he'd been at work. On the way back he turns on his show, only to discover that the record is skipping.
1.70a. Variant: The music stops and the man dies.
1.70a answer: The same, except it's a tape breaking instead of a record skipping. (from Michael Killianey) (See also #1.31a, #1.59, and #1.75c.)