Two former Naval Academy midshipmen testified Monday that they believe a Navy doctor who hosted them in his home used a hidden camera to tape them having sex with their girlfriends and record other midshipmen engaged in sexual acts.

The two men said they found digital videos and tape recordings of themselves and other midshipmen in Cmdr. Kevin Ronan's three-bedroom house near the Annapolis military school. A tiny camera was allegedly placed inside an air purifier that was pointed toward the bed in a guest room.

"Obviously I was pretty shocked finding those," said one of the men, later dabbing his eyes with a tissue as he struggled to compose himself during a hearing for Ronan at the Washington Navy Yard.

Ronan is assigned to the Navy's Bureau of Medicine and Surgery, but was previously a team physician for Naval Academy sports teams and a medical officer in the midshipman dorm. He also was designated as a midshipman sponsor by the academy, meaning he hosted several students on weekends and for overnight visits.

Ronan did not speak during the Article 32 hearing, which is the military version of a civilian grand jury review. A Navy commander who heard the evidence Monday will make a recommendation on whether Ronan should face court-martial on the charges he faces.

Ronan is charged with 18 counts related to conduct unbecoming an officer, obstruction of justice, violating federal wiretapping law and a Maryland law against making secret recordings. He could be sentenced to up to 18 years in prison if convicted on all charges.

His lawyer alleges the tapes were part of a plot by one of the former midshipmen to extort money from Ronan to help cover $127,000 the man owed the government after being expelled from the academy in January for poor grades. The man denied the allegation Monday.

The Associated Press is not identifying the two former midshipmen who testified because they were allegedly videotaped without their consent. One is an ensign in the Navy but was a midshipman when the tapes were discovered in January. The man who was expelled now lives in Gainesville, Fla.

The two men said Naval Academy students were fond of Ronan, who was team doctor for sports teams that included men's soccer and gymnastics. Ronan's house was full of electronics, including flat screen televisions, a foosball table and video games. They referred to him as "Doc," often spending the night in one of his two guest rooms dubbed "the blue room" and "the red room."

The midshipman who was expelled said he went to live at Ronan's house after he left the academy. In late January, he found a DVD titled "lectures" in Ronan's room, watched it and saw footage of the ensign having sex.

He and the ensign claim they found video tapes and DVDs of themselves and several other midshipmen engaged in sexual acts in Ronan's guest rooms. Eventually, they found the camera and a receiver attached to the back of the television in Ronan's room. They filmed their search with a digital camera, then took some of the videos and DVDs and left the house. The ensign turned the material over to Navy investigators.

A later search of Ronan's house did not turn up additional tapes that the two former midshipmen claimed were there, including DVDs in Ronan's sock drawer. Investigators did find a receiver and the air purifier stored in the attic.

Ronan's attorney, William Ferris, said the Navy's case has flaws. He said Navy prosecutors only have recordings of the two men and a third midshipman. Four others outlined in the charges were allegedly shown on the DVDs that investigators never found. Maryland law cited by Navy prosecutors also might not cover secret taping in a private home, he said.

Ferris implied that the men may have made the tapes themselves. He claimed the ensign looks directly at the camera several times while having sex with his girlfriend. The ensign testified he was glancing at the television and that the purifier with the camera was on top of the TV.

"This is a behavior that is extraordinary unless someone knows he is being recorded," Ferris said.