A senior Ohio Air Force base official pleaded guilty on Monday to sexual misconduct and adultery, blaming extramarital affairs he had with married female subordinates and inappropriate sexual advances he made toward others on getting "caught up in a cycle of sin."

Chief Master Sgt. William Gurney was the senior enlisted man at the Air Force Materiel Command at Wright-Patterson Air Force Base near Dayton, Ohio, when allegations of sexual impropriety surfaced in 2009.

While entering his guilty pleas to 13 counts at Scott Air Force Base in southwestern Illinois, the 27-year Air Force veteran told Air Force Col. W. Thomas Cumbie, the military judge overseeing his case, about indiscretions dating back to mid-2007. He said he had had sex with four married women based at Wright-Patterson who were lower in rank than him, and that he exchanged sexually explicit pictures with and kissed or fondled female subordinates.

Gurney also told Cumbie that he twice had sex with his wife in front of a married enlistee whose husband was unaware.

"I was caught in a cycle of sin," Gurney said, before admitting he "failed not only as an airman but as a husband."

Cumbie tossed out an obstruction of justice count against Gurney, but Gurney still faces five counts to which he has pleaded not guilty. Those counts allege that he made sexual advances toward two subordinates that amounted to mistreatment, that he fondled one of those women and that he abused his authority.

Court martial proceedings began Monday on those five counts, and a six-person jury was chosen from among ranking officers at Scott Air Force Base. Gurney could face up to 14 1/2 years in prison and a dishonorable discharge for the charges he pleaded guilty to Monday, and an additional four years in prison if convicted of the five other counts. Opening statements are expected to begin Tuesday.

Among the charges Gurney pleaded guilty to were seven counts of dereliction of duty _ one for each enlisted woman he was accused of making inappropriate advances toward _ and four counts of adultery. He also admitted to using his military-issued cell phone and computer to exchange explicit e-mails and texts, and to having had sex with his wife while a female enlistee watched.

Prosecutors and defense attorneys told Cumbie that Gurney's guilty pleas were made without any promise of a lesser punishment or the dismissal of other counts.

None of the women mentioned in the charges was in the courtroom as Gurney described their encounters for the first time in public. Cumbie has told attorneys not to discuss the case publicly.

Gurney had transferred to Wright-Patterson in 2008 from Hill Air Force Base in Utah, where he was command chief of the Ogden Air Logistics Center and 75th Air Base Wing.