DENVER (AP) — Only hours before women marched through many U.S. cities in January, Christopher Cleary set off a manhunt when he posted a Facebook message threatening to kill "as many girls as I see" in retaliation for years of romantic rejection.

Cleary, 27, called himself a virgin who never had a girlfriend, stoking fears of another deadly rampage by a man blaming women for his problems. When police tracked his cellphone and arrested the Colorado resident at a McDonald's restaurant in Provo, Utah, Cleary said he had been upset and wasn't thinking clearly.

The frightening Facebook post fit a p...