The two hostage-takers may be charged with sexual assault.

PHOENIX (AP) – Probable criminal charges against two inmates who held a female corrections officer hostage during a 15-day standoff at an Arizona prison could include sexual assault, according to the governor’s general counsel.

In documents obtained by The Associated Press on Wednesday, Gov. Janet Napolitano’s top attorney, Tim Nelson, listed sexual assault among seven probable charges the inmates would face stemming from last month’s standoff.

One of the inmates, a native of Lewiston, Maine, is scheduled to be returned to his home state as part of the deal with Napolitano that ended the standoff. The other will be transferred to a prison in Wisconsin.

Nelson listed the charges in an e-mail sent to Corrections Director Dora Schriro on Feb. 1, hours before the inmates surrendered and released the woman. The other guard taken hostage, a man, had been released Jan. 24.

The inclusion of sexual assault is the first on-the-record documentation that at least one sexual assault occurred during the hostage situation.

Schriro and Napolitano spokeswoman Jeanine L’Ecuyer declined Wednesday to comment on the e-mail’s contents or whether sexual assaults occurred. Nelson did not immediately return a call to his office late Wednesday.

“I’m honor-bound to honor those commitments,” Schriro said, referring to the guards’ privacy concerns and requests that no medical information be released.

Ricky Wassenaar, 40, and Steven Coy, 39, overcame two officers at a Buckeye prison kitchen before dawn on Jan. 18. Wassenaar shaved and changed into an officer’s uniform and gained entry into a prison guard tower, where he overpowered two other officers.

Negotiators worked virtually around the clock to get the two guards out safely without storming the three-story tower and risking a bloody clash.

In exchange for releasing the two guards, Coy will be transferred to a prison in Maine, with Wassenaar going to a prison in Wisconsin. The transfers were the only promises officials made, Napolitano said last week. Meanwhile, the two are in federal custody.

Media outlets, including The Associated Press, have reported that some sexual assaults occurred, but state officials have declined to confirm that. Nelson’s e-mail was among documents released in response to a public records request by several news organizations.

The Associated Press has reported that a female kitchen worker was sexually assaulted by Coy. And, a state official familiar with the negotiations spoke on condition of anonymity, saying the female guard was sexually assaulted.

Other charges listed in Nelson’s e-mail included kidnapping, promoting prison contraband and being a felon in possession of a weapon. Documents also show that the prison’s first alarm wasn’t sounded until more than one hour after the standoff began.

At one point, a corrections officer saw two hostages handcuffed in the watchtower and walked away thinking they were engaged in “horseplay,” the Arizona Republic reported Thursday.

Bill FitzGerald, a spokesman for the Maricopa County Attorney’s Office, declined to discuss possible charges against the two inmates. But investigator Tom McHugh said the county attorney’s office has “enough information to proceed now” with charges.

Other documents obtained Wednesday gave fresh details of authorities’ efforts during the standoff. They show officials made several attempts to install listening devices in the tower, and researched whether to end the standoff by secretly drugging the inmates’ food so they would fall asleep. Experts rejected that idea.