On Tuesday evening, beneath a cloud-veiled full moon, Ken Neville exited through the glass front doors of the Marin County Jail, newly freed. After two weeks of trial in Superior Court, it had taken less than a day for jurors to arrive at a verdict: not guilty.

“I’m shocked,” he said, before he was shuttled away to a family home in San Leandro. “I did not expect this.”

Mr. Neville, a soft-spoken 56-year-old white man,…