PHOENIX - An Arizona inmate pleaded guilty Monday to raping a prison teacher and will likely be sentenced to spend the rest of his life behind bars for a crime that prompted unprecedented fines against the state Department of Corrections for failing to protect the teacher.

Jacob Harvey changed his plea to guilty without a plea agreement, admitting to charges of rape, kidnapping and aggravated assault with a weapon at a routine pre-trial hearing in Pinal County Superior Court. Pinal County Attorney's Office spokeswoman Tiffany Davila said Harvey faces up to life in prison on the rape charge alone when he's sentenced next month.

The new sentence won't start until his current term ends in 2041.

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The woman is suing the state over the January 2014 attack in a classroom at the Eyman state prison in Florence that she says has sent her into therapy and made it difficult for her to sleep. She was in the Pinal County courtroom when the 21-year-old entered his plea.

Arizona prison officials are appealing a $14,000 fine state workplace safety regulators levied for failing to protect a teacher. The action by the state Division of Occupational Health and Safety marked a rare fine levied by the state agency against the Department of Corrections.

The agency also is investigating the April 13 sexual assault of a corrections officer at the state prison in Yuma.

Arizona has faced intense criticism over the attack on the teacher. Prison officials sent out only a vague press release that referred to an assault on an employee after the January 2014 rape. The details of the assault came to light only after The Associated Press obtained documents under a public records request and interviewed people familiar with the case.

The attack raised questions about prison security because the teacher was put into a room full of sex offenders with no guards nearby and no closed-circuit cameras. She had only a radio to call for help.

Harvey was in the first year of a 30-year sentence for raping a Glendale, Arizona, woman in November 2011. Just 17 at the time, he had knocked on the woman's door in the middle of the day, asked for a drink of water, then forced his way inside, where he repeatedly raped and beat her while her 2-year-old child was in the apartment. He fled naked when the woman's roommate arrived home.

He was arrested after DNA evidence connected him to the crime, and he pleaded guilty.

Harvey was initially classified as a "Class 4" security risk, one notch lower than the highest level. Six months later, despite violating prison rules at least once, he was reclassified at a lower level.

In an earlier AP interview, the now-35-year-old teacher said she mainly blames Department of Corrections Director Charles Ryan, who she says allowed lax training, staffing shortages and poor security at the prison about 40 miles south of Phoenix. The AP does not identify those who say they are victims of sexual assault.

The attack occurred Jan. 30, 2014 at the Eyman prison's Meadows Unit, which houses about 1,300 rapists, child molesters and other sex offenders. The teacher was administering a high school equivalency test to about a half-dozen inmates in a classroom with no guard nearby and only a radio to summon help.

The Department of Corrections issued only a bare-bones press release after the attack, but the AP pieced together what happened based on interviews and investigatory reports obtained under the Arizona Public Records Act.

After the last of the other inmates left, Jacob Harvey asked the teacher if she could open the bathroom and then attacked her, she told investigators and the AP. Harvey stabbed her in the head with a pen, forced her to the ground and raped her.

The teacher said that she screamed for help, but none came. Afterward, Harvey tried to use her radio to call for help. It had apparently been changed to a channel the unit's guards didn't use, so Harvey let the woman use a phone, she said in the interview.