Jaime Grijalva, 28, was picked up by police about a half-mile away as he walked near Suffolk Avenue and Fulton Street, Det. Sgt. Jeffrey Walker said.
Grijalva was driving his 1998 Mercedes south about 3:30 a.m. on Joshuas Path when he lost control of the car at a bend in the road and hit a utility pole at the intersection of Calebs Path, police said.
"It was a horrific scene," Walker said. "The vehicle was off the road, up against the utility pole. There was obvious damage."
Teodoro Albin, 22, of Union Boulevard in Bay Shore, died at the scene.
Albin is the father of Grijalva's sister's child, Walker said.
Grijalva's cousin, Ramiro Grijalva, also of Bay Shore, was taken by helicopter to Stony Brook University Medical Center, where he was treated for non-life-threatening injuries.
It is unclear whether Jaime Grijalva was aware of the severity of Albin's wounds.
"He walked away from the scene," Walker said. "I don't know what he knew."
Grijalva consented to a blood test and police are awaiting the results. He was charged with driving while intoxicated and leaving the scene of a personal injury accident.
His arraignment was scheduled for Sunday in First District Court in Central Islip, police said.