A prison standoff that stretched to 12 days Thursday could be the lengthiest prison hostage situation in the United States in at least 50 years, an expert said.

Other standoffs include an 11-day incident in 1987, when Cuban detainees took control of a penitentiary in Atlanta and held more than 100 hostages. Inmates in Lucasville, Ohio, also staged an 11-day standoff in 1993, taking 12 guards hostage to stop mandatory tuberculosis testing.

Both ended in negotiated surrenders.

Robert McCrie, a professor of law and police science at John Jay College of Criminal Justice (search) in New York, said the standoff at Arizona State Prison Complex-Lewis (search) was probably the longest in at least five decades.

Negotiators spoke briefly to the female hostage Wednesday.

"The indications are that she is doing OK," said Alan Ecker, a spokesman for the state Department of Corrections. He offered no other details.

Authorities were trying to ensure the hostage's safety, corrections spokesman Michael Murphy said Thursday.

"Because we value the life of that officer so dearly, it will take as long as it takes," Murphy said.

The two inmates in the high-security section of the prison took two officers hostage in a guard tower before dawn on Jan. 18. The other officer, a man, was released Saturday.

Prison officials have released few details about the officers, the inmates or how the takeover happened, saying they don't want to hurt negotiations.

Negotiators have either spoken to or seen the female officer at least six times over the course of the ordeal at the 4,400-inmate facility west of Phoenix.

The standoff began after an inmate attacked a guard in a kitchen area. That prisoner and another inmate then got into an observation tower where the two guards were stationed. The guard tower, in the middle of the prison grounds, is believed to be stocked with weapons.