FORT BRAGG, N.C. - The lead prosecutor in a sexual assault case against a U.S. Army general wanted the most serious charges dropped after he became convinced the accuser had lied about crucial evidence.

According to testimony, after Lt. Col. William Helixon shared those concerns with his superiors, he was referred for a mental health evaluation and removed from the case.

The testimony came at a hearing for Brig. Gen. Jeffrey A. Sinclair, who faces a court-martial on charges that include physically forcing a female captain under his command to perform oral sex.

Sinclair's attorneys have asked a judge to dismiss the most serious of the charges against him, alleging top brass at the Pentagon have unlawfully interfered with prosecutorial decisions in the case.

Helixon was removed from the case last month after a superior officer, Brigadier Gen. Paul Wilson, visited him in a Washington hotel room on Feb. 8.

Wilson testified Tuesday that Helixon appeared drunk and suicidal. Wilson said Helixon didn't want to pursue the case, but thought it was of strategic importance to the military's crackdown on sexual assaults.

"He was in the midst of a personal crisis. He was crying. He was illogical," Wilson said.

Sinclair, who was the deputy commander of the 82nd Airborne and a rising star among the U.S. Army's top battle commanders, is fighting charges that could land him life in a military prison if convicted. He has pleaded not guilty to eight criminal charges including forcible sodomy, indecent acts, violating orders and conduct unbecoming an officer and a gentleman.

Lawyers for the married father of two have said he carried on a three-year extramarital affair with an officer under his command during war tours in Iraq and Afghanistan. The admission of an affair will almost certainly end his Army career.

The case against Sinclair is believed to be the most senior member of the U.S. military ever to face trial for sexual assault.

In pretrial hearings, prosecutors painted Sinclair as a sexual predator who abused his position of authority to prey on a subordinate. They also say he threatened to kill her and her family if she told anyone of their relationship.

But the lead prosecutor became convinced the accuser lied to him when she testified in January about evidence collected from her cellphone. The female captain testified that on Dec. 9, shortly after what she described as a contentious meeting with prosecutors, she rediscovered an old iPhone stored in a box at her home that still contained saved text messages and voicemails from the general. After charging the phone, she testified she synced it with her computer to save photos before contacting her attorney.

However, a defense expert's examination suggested the captain powered up the device more than two weeks before the meeting with prosecutors. She also tried to make a call and performed a number of other operations.

Wilson testified that Helixon was distraught that the accuser had lied to him. Wilson said he took Helixon to the emergency room of a nearby military hospital for a mental health evaluation. Though a psychiatrist declined to admit him for treatment, Wilson said he told Helixon's immediate superior back at Fort Bragg that the prosecutor was no longer fit to handle the case.

"He was not fit for any kind of duty," Wilson said.

After Helixon's removal, a new prosecutor was assigned to take the case to trial, which is set to begin this week.

Neither the defense nor prosecutors called Helixon to testify.

Sinclair's defense lawyers suggest it is the general who is the victim, both of a jealous ex-lover and of overzealous prosecutors facing intense pressure from top military and political leaders to send a message that sexual misconduct will not be tolerated.

"We're in a remarkable place," Richard Scheff, Sinclair's lead defense lawyer, said this week. "The chief witness lied under oath. The lead prosecutor resigned because he found her untruthful and non-credible. The Army's senior leaders agree with his assessment. And yet we're going to trial."

The Associated Press does not publicly identify the alleged victims of sexual assaults.

Prosecutors have declined to comment about the case outside court proceedings.

It is extremely rare for such a high-ranking military officer to face a jury. Under the military justice system, members of the panel must be senior in rank to the accused - ensuring that Sinclair will be judged by a jury of generals.

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Follow Associated Press writer Michael Biesecker at www.twitter.com/mbieseck.