Napa County sheriff's detectives arrested two Vacaville residents Monday in connection with the beating and robbery of a man at Lake Berryessa in September, a sheriff's captain said.

Both suspects, and a third suspect who is still at large, knew the victim, also a Vacaville resident, whom they allegedly left for dead on the side of state Highway 128 near the Markley Cove Resort at the southern end of the lake, sheriff's Capt. Tracey Stuart said.

The suspects and victim, 42-year-old Dustin Wayne Valentine, were among a group of people who visited the lake on Sept. 16, Stuart said.

The suspects took Valentine's wallet, jacket and cellphone in the robbery, Stuart said.

A motorist called the sheriff's office to report a man in a lane of traffic in the 7500 block of Highway 128, Stuart said.

Deputies found Valentine just after midnight on Sept. 17, unconscious and suffering from major head injuries.

He was taken to the Capell Valley Fire Department in Napa by ambulance then flown to John Muir Medical Center, Stuart said. He survived and has since been released from the hospital.

"We didn't think he was going to make it," Stuart said Wednesday afternoon.

Stuart said a persistent investigation and information from people who knew what happened to Valentine led to the identification of Dairius Anthony Hill Anderson, 21, Cherena Charise Martinie, 23, and Kenneth Martin Moen-Pfister, 24, all of Vacaville, as the suspects.

Anderson was arrested at a home in the 400 block of Wilmington Way in Vacaville on suspicion of attempted murder and robbery, and Martinie was arrested at an apartment at 1501 Alamo Drive in Vacaville for battery with serious bodily injury and robbery.

Moen-Pfister is still at large. He is white, 5 feet 10 inches tall and weighs 140 pounds, with brown hair and hazel eyes. He likely will face robbery charges only, Stuart said.

Anyone with information on the case is asked to call sheriff's detectives at (707) 253-4591.