A 56-year-old Snohomish man had set his Tesla Model S on Autopilot and was looking at his cellphone on Friday when he struck and killed a motorcyclist in front of him in Monroe, court records show.

A Washington State Patrol trooper arrested the Tesla driver at the crash site on Highway 522 at Fales Road shortly before 4 p.m. on suspicion of vehicular manslaughter, according to a probable cause affidavit.

The motorcyclist, Jeffrey Nissen, 28, of Stanwood, died at the scene, records show.

The Tesla driver told a state trooper he was driving home from having lunch in Bothell and was looking at his phone when he heard a bang and felt his car lurch forward, accelerate and hit the motorcyclist, according to the affidavit.

The man told the trooper his Tesla got stuck on top of the motorcyclist and couldn’t be moved in time to save him, the affidavit states.

The trooper cited the driver’s “inattention to driving, while on autopilot mode, and the distraction of the cell phone while moving forward,” and trusting “the machine to drive for him” as probable cause for a charge of vehicular manslaughter, according to the affidavit.

The man was booked into the Snohomish County Jail and was released Sunday after posting bond on his $100,000 bail, jail records show.