CHICAGO (AP) — Authorities in Illinois and Indiana searched Friday for a convicted murderer who was mistakenly released from custody in Chicago, with the two sides differing over whether a paperwork error could be to blame.

Steven L. Robbins, 44, was released Wednesday evening from a jail in Chicago, where he had been taken to answer to a drug charge in Cook County Circuit Court. That charge was dropped, and Robbins was freed instead of being sent back to Indiana to continue serving a 60-year murder sentence.

Indiana Department of Corrections said in a news release that "for reasons yet unknown, the offender was released by Illinois authorities without being held for return."

The department submitted paperwork telling Illinois officials that Robbins was supposed to be returned to Indiana, spokesman Douglas Garrison said Friday.

"It's quite clear that all of the paperwork from IDOC was in order, so that they would have known that he was supposed to be returned to us," Garrison said.

The Cook County Sheriff's Office said it was investigating how Robbins was released. Sheriff's office spokesman Frank Bilecki told the Chicago Sun-Times that an initial investigation showed there was no paperwork indicating Robbins should be held.

Bilecki did not respond to requests for comment Friday.

Robbins, a Gary, Ind., native, was serving the decades-long sentence for murder and weapons convictions out of Marion County in Indiana.

Witnesses to the 2002 killing told police at the time that Robbins was arguing with his wife outside a birthday party in Indianapolis when a man intervened, telling Robbins that he should not hit a woman, according to court documents. The witnesses said Robbins then retrieved a gun from a car and shot the man, Rutland Melton, in the chest before fleeing.

Robbins was also found guilty of carrying a handgun without a license.

He started serving his sentence in October 2004 and his earliest projected release date was more than 16 years from now, on June 29, 2029.

Both Illinois and Indiana have issued arrest warrants for Robbins. Officials in both states are asking for the public's help to apprehend him.