DENVER (AP) — Prosecutors say they only learned after a judge set $400,000 bond for a truck driver accused of causing a fiery pileup that killed four people on a Colorado highway that he had tried to flee the scene of the collision.

In a filing Monday, they asked a judge to require that the now-released man be required to wear a GPS monitoring device.

Rogel Lazaro Aguilera-Mederos, 23, of Houston, was released over the weekend after being charged with four counts of vehicular homicide and other crimes in the April 25 collision near Denver.

Police have said the truck was going at least 85 mph (137 kph) on a part of Interstate 70 where commercial vehicles are limited to 45 mph (72 kph). Authorities described the resulting crash as a 28-vehicle chain reaction wreck that ruptured gas tanks, causing flames that consumed several vehicles and melted parts of the highway just after it descends from mountains west of Denver.

Jefferson County district attorney spokeswoman Pam Russell said Tuesday that she could not provide more information about investigators' conclusion that Aguilera-Mederos tried to leave the scene.

Robert Corry, Aguilera-Mederos' attorney, did not immediately return a phone message seeking comment Tuesday.

According to previously filed court documents, Aguilera-Mederos spoke to police at a hospital where he was treated for injuries he received in the crash. The document says he was transported to the hospital for treatment and then taken to a police department for more questioning.

Aguilera-Mederos was released from jail Saturday after paying bond, which is typically 10% of the total amount set by a judge. Corry, his defense attorney, has said the crash was an accident caused by a mechanical failure of the truck his client was driving.

Authorities have said the semitrailer was destroyed in the crash, making a mechanical inspection impossible.

Prosecutors, though, have argued that Aguilera-Mederos showed "extreme indifference to the value of human life."

A judge has not scheduled a hearing yet on prosecutors' request for GPS monitoring. KDVR-TV first reported the request.

According to the court's original order, Aguilera-Mederos cannot drive commercial vehicles and must remain in Colorado while out on bond.