GRAND ISLAND, Neb. (AP) — An Ohio man charged with first-degree murder in the fatal stabbing of a couple at an Interstate 80 rest stop in Nebraska has pleaded not guilty by reason of insanity.

James Thompson Jr., 22, of Elyria, Ohio, entered the plea Tuesday, the Lincoln Journal Star reported. Thompson is also charged with attempted murder, attempted robbery, fleeing arrest and a string of weapons counts in the June 19 stabbings of 72-year-old Gary Weaver and his 71-year-old wife, Mary Weaver, both of Eureka, Missouri.

Investigators have said that witnesses reported hearing Thompson demand the keys to a Jeep that was being towed behind the Weavers' RV before he stabbed them both at a rest area near Grand Island. Both were critically injured, and Gary Weaver later died from his injuries at a hospital.

Part of the attack was captured on a trucker's dash cam, investigators say. Police have said Thompson fled the rest area in a car, and a Nebraska State trooper later spotted him exiting I-80 at nearby Wood River. A chase ensued, and investigators say Thompson sped away at speeds of 120 mph (193 kph) before crashing into the Platte River. He was arrested nearby with blood on his shirt and several cuts on his hand, police said.

Thompson's public defender had earlier raised questions about his client's mental health, but Thompson was found competent to stand trial on Oct. 1.

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