McALESTER, Okla. (AP) _ A convict at the maximum-security Oklahoma State Penitentiary who took a nurse captive for 17 hours released her after holding a news conference in his cell, then tried to hang himself with an extension cord, guards said.

Timothy Owens, 23, promised three reporters who'd gathered at his cell Monday night a spectacular ending to the ordeal, but guards who rushed his cell cut him loose and took him away screaming instead.

In his 15-minute news conference, Owens complained about his armed robbery conviction, contending he could prove he was innocent.

Nancy Steele, a 36-year-old nurse at the prison infirmary, was taken away crying, spokesmen said.

''She's safe, but she's exhausted, of course,'' said Joyce Jackson of the Corrections Department.

The incident began when Owens lured Ms. Steele, who was accompanied by a guard, into his cell at 5:30 a.m. Monday by complaining he was ill, Ms. Jackson said. Owens pulled her inside but shut the guard out by pushing his bed against the cell door.

All prisoners in Owens' cellblock were removed and all of the prison's cells were locked for the day, said Ms. Jackson. A prison negotiating team, including a psychologist, talked with Owens through the bars of his cell or from down the hall all day.

At 2 p.m., negotiators got Owens to agree to trade a knife fashioned from a staple gun for some food. But they were not sure he was disarmed.

Late Monday, he agreed to release his hostage if three reporters were allowed to interview him. After his news conference, he released the woman at 10:10 p.m., then tried to hang himself.

Owens did not have a history of violence, Ms. Jackson said. He was sent to Oklahoma State Penitentiary following an escape attempt at another prison.

He began serving a 10-year sentence for armed robbery in 1980, prison officials said. Assistant District Attorney Pat Jackson said Owens pleaded guilty in Canadian County in June 1979 to charges of second-degree burglary, grand larceny and robbery with a firearm.

Jackson also said Owens was charged in Pottawatomie County with armed robbery and in Florida with armed robbery. He said both of those charges were filed in 1979, but he did not know the disposition of those charges.

Owens showed reporters copies of statements by witnesses and hotel receipts indicating he was in Jacksonville, Fla., when two armed robberies he's charged with occurred in 1979.