Morgan, who turns 23 in about a week, was sentenced to seven years after his probation was revoked. He had pleaded guilty to burglary charges in Hughes County and to receiving stolen property in Cleveland County.
Eike said the man had been at the prison since April.
“Maybe he wanted to leave because he's about to have a birthday,” she said.
Two inmates escaped from the same prison less than a week ago but were recaptured two days later at a motel in Del Rio, Texas.
Damario Love, 26, and Anthony Brinsfield, 31, were reported missing Sunday morning.
Love had been convicted of second-degree robbery in Tulsa County, while Brinsfield was convicted of possession of a firearm during commission of felony and drug charges in Pottawatomie County.
Two other inmates escaped from the prison two weeks ago, but were caught less than a day later, officials said.