He was the houseguest from hell, according to prosecutors.

Lawrence Lee Buffington, 46, was arrested on suspicion of brutally beating his stepbrother — who had offered him a place to stay at his Redwood City home — with a hammer June 9, San Mateo County District Attorney Steve Wagstaffe said Tuesday.

The Redwood City victim, who survived the attack but suffered a fractured skull requiring multiple sutures, should have trusted his instincts when he “reluctantly” offered his stepbrother a place to stay, Wagstaffe said.

Buffington received the offer to stay at the Redwood City home after he had a fight with his girlfriend, prosecutors said. The next morning, however, Buffington accused his stepbrother of having an affair with his gal pal. Buffington based the allegation on a photograph he found, Wagstaffe said.

He allegedly “grabbed a hammer and struck the victim in the head multiple times while screaming he was going to kill him,” Wagstaffe said.

Buffington appeared with his court-appointed attorney Tuesday, but did not enter a plea. The case was continued to July 10, and he remains in custody on no-bail status.