Residents of Citrus Heights awoke on Thursday to the lingering shock that their neighbor, a man who liked to tinker with his motorcycle in front of his neat beige stucco house, had been accused of being one of America’s most notorious serial rapists.

“It’s crazy — they were looking for this guy for 40 years and he was right here under our noses,” said Ashley Piorun, who lives five houses down from Joseph James DeAngelo, the former police officer who the authorities now say was the Golden State Killer. “We were shell shocked to find out.”

This suburban neighborhood of well-kept homes, east of Sacramento, is a classic California housing tract of cul-de-sacs and towering palm trees. Ms. Piorun calls it a “quiet, sweet, boring neighborhood.”