DENVER (REUTERS) - Defence attorneys for the 25-year-old man accused of killing 12 people in a shooting rampage at a Denver-area movie theatre have offered to have him plead guilty in exchange for a life prison term, according to court documents filed on Wednesday.

Lawyers for James Holmes said in the court papers that prosecutors have not yet responded to their offer, which would spare their client the death penalty. Holmes is scheduled to be in court on Monday for a hearing in the high-profile case.

A spokesman for the Arapahoe County District Attorney's Office could not immediately be reached for comment.

"Prior to arraignment, Mr Holmes made an offer to the prosecution to resolve the case by pleading guilty and spending the rest of his life in prison without the opportunity for parole," lawyers for Holmes say in the papers.

The defence attorneys said in the pleading that if prosecutors agree to the plea deal the case could be resolved at Monday's hearing.

Holmes faces multiple counts of first-degree murder and attempted murder stemming from the July 20 rampage that also wounded 58 people and was one of the deadliest mass shootings in United States history.

His lawyers had been expected to mount an insanity defence for the former University of Colorado neuroscience graduate student who surrendered to officers outside the theatre in the Denver suburb of Aurora within minutes of the mass killing.