(KTEN) — Oklahoma Attorney General Gentner Drummond is asking the U.S. Supreme Court for a new trial for death row inmate Richard Glossip.

Glossip, now 60 years old, received the death penalty for the 1997 murder-for-hire killing of his boss, motel owner Barry Van Treese.

Drummond believes the conviction should be set aside because of misconduct.

"The district attorney had destroyed not one key evidence, but about 10 pieces of key evidence in this trial," said state Rep. Justin Humphrey (R-District 19). "They also had their No. 1 witness change their testimony to meet what the medical examiner was reporting."

If a new trial is granted, it would be held in Oklahoma County District Court.