DENVER (CBS4) – Jury selection is under way for a man accused of sexually assaulting a woman in a concourse at Denver International Airport.

Noel Bertrand, a former Marine from Portland, is charged with kidnapping and sexual assault in a largely deserted A Concourse just after midnight on April 12, 2011.

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The woman says she was talking with Bertrand after missing a flight when the conversation turned violent and that he he assaulted her soon afterwards. Surveillance video from the airport shows Bertrand walking with the accuser in the concourse.

Two mechanics who work for Frontier Airlines said they saw the alleged assault from outside and ran inside to help.

Bertrand claims the sex was consensual.

In a pre-trial hearing images were shown of the accuser’s swollen left eye and bruises to her hand. She told police her head was slammed into the ground during the attack. A detective also testified the accuser was headed to Illinois to become a nun.

Denver Police Detective Edward David testified a year ago that the two walked from a bar to a gate together and talked for about 20 minutes. The accuser told police that when they changed seats and moved closer to the window, that is when Betrand did a, “180 turn. A Dr. Jekyll and Mr. Hyde change,” testified David.

The detective who interviewed Bertrand following the incident said Bertrand’s first comment was that he was a Marine recently discharged and that the incident would damage his image. Bertrand also told allegedly police he prefers a dominant-submissive role and believed the woman wanted to be submissive. He allegedly said the situation was a case of “animal attraction,” that “it was heated,” and that he knows how to “read women” and this particular woman “was resisting,” which told him that she wanted it.

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The mechanics — Kris Musil and Mark Adams — were out on the tarmac and said they then saw the violent situation going on inside the concourse. They called 911 and quickly went inside the building.

“She was down on ground when we first got there. That’s when saw him take one last swing at her,” Musil said during a June 2011 ceremony where Denver police honored the two mechanics.

Musil and Adams say they intervened and took command of the situation until police arrived.

They said the woman was very shaken up and that she was having an asthma attack when they arrived. They helped her find her inhaler in her luggage.

“She mouthed ‘Thank you’ to us when he finally let her go,” Musil said.

The Denver Post reported that Bertrand was a Marine for about 6 years, from 2003 to 2009, and that he won the Navy and Marine Corps Achievement Medal.

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Bertrand’s attorney said in pre-trial hearings there were inconsistencies between what the accuser told police following the incident, and then later to hospital staff who examined her. The defense also pointed out that there were statements from other witnesses who passed by telling police they thought the two were a couple.