ARLINGTON — The man and woman were looking for a place to park their van for the night and go to sleep. The rest stop on I-5 was full, so they went searching through north Snohomish County.

They never found a spot.

A 20-year-old man from Lake Stevens has been charged in Snohomish County Superior Court with vehicular homicide and hit-and-run fatality accident.

The pair found themselves driving south of Arlington around 2:45 a.m. on March 16. While passing through the intersection of 67th Avenue NE and 152nd Street NE, they were struck from behind by an Audi A4, prosecutors allege. Both vehicles went spinning. The van flipped onto its roof and slid into a utility pole. The car ran off the road and into someone’s yard, crashing into a tree.

The passenger of the van, 49, pulled herself out of the wreckage, but collapsed as she walked toward sheriff’s deputies. She was taken to Cascade Valley Hospital in Arlington. She had fractures in her spine, nose, face and pinky finger.

The driver, 41, was unconscious. He was taken to Providence Regional Medical Center in Everett with a head injury, where doctors performed surgery to reduce brain swelling.

He couldn’t be saved and was taken off life support on March 20. The Snohomish County Medical Examiner’s Office said the cause of death was a traumatic brain injury.

The defendant reportedly had left the scene. A deputy found him at about 5 a.m., walking down 152nd Street and trying to catch a ride. He was wet, muddy, smelled of alcohol and his speech was slurred, according to court papers.

At first he claimed a friend had dropped him off, but eventually said he was driving the Audi, according to charging papers. He said the van stopped abruptly and that he didn’t have time to stop. He ran because he was scared, he said.

Eight hours after the crash, when detectives obtained a search warrant, the defendant’s blood-alcohol test came back as 0.11. The legal limit is 0.08. The test also came back positive for THC, the active ingredient in marijuana.

The man was booked into the Snohomish County Jail, where he remained Monday. Bail was set to $500,000.

Zachariah Bryan: 425-339-3431; zbryan@heraldnet.com. Twitter: @zachariahtb.