The Manhunt

Christopher Goffard, Joel Rubin and Kurt Streeter: The man emerged from a charcoal-gray pickup and approached the hotel check-in counter. He wanted a room and the Internet pass code. He was 6 feet tall, with a weightlifter's build and military posture. But he could transform his soft, round face into a picture of amiability. He struck the night manager as personable and disarming.

Inside Room 116 of the Hi View Inn & Suites in Manhattan Beach, he stared at his Facebook page and a lifetime's worth of grudges. It is not clear how long he had labored on the unusual document on the screen.

It was a rambling, free-associating screed in which he asserted firm opinions on politicians, journalists,…