A motorist was high, speeding and checking a cellphone for directions leading up to when he hit a barrier wall along a south metro interstate and killed his girlfriend last Memorial Day weekend, according to charges.

James R. Lapsley, 21, of Prior Lake, was charged Wednesday in Dakota County District Court with criminal vehicular homicide in connection with the crash on May 26, 2018, on Interstate 35W in Burnsville.

The wreck about 7:20 a.m. on southbound I-35W near Burnsville Parkway killed Kayli K. Thompson, 19, of Burnsville. Lapsley was treated at Hennepin County Medical Center for his injuries. Both had on their seat belts, the State Patrol said.

Lapsley remains free ahead of his first court appearance on July 8. Messages were left for him and his attorney seeking a response to the allegations.

“This appears to be another tragic example of impaired driving that has claimed a life on our roads,” County Attorney James Backstrom said in announcing the charges.

According to the criminal complaint:

Officers arrived at the scene to find Lapsley out of his car, and Thompson was dead at the scene.

Lapsley’s had bloodshot and glassy eyes, and his speech was slurred. Authorities tested his blood and it came back positive for THC, the active ingredient in marijuana.

A motorist who stopped at the crash scene said he saw Lapsley’s car “driving erratically and at a high rate of speed,” the charges read. He saw the car hit the median barrier twice before it went past him and out of view. The witness next saw it in a ditch ahead.

Lapsley told officers that he and Thompson had been fishing that morning on Prior Lake and were heading to her house before the crash.

He said that they were checking the GPS function on her phone and passing it back and forth at the time. He denied having been drinking alcohol or being under the influence of a controlled substance recently.

Lapsley estimated he was driving 55 miles per hour when he slammed on the brakes before hitting the barrier wall. A State Patrol investigation determined, however, that he was going about 91 mph a mile north of the crash scene and was traveling 83 mph at the time of impact.