Sinclair, the 51-year-old former deputy commander of the storied 82nd Airborne Division, is believed to be the highest-ranking U.S. military officer ever court-martialed on sexual assault charges. He could get life in prison if found guilty.
Sinclair pleaded guilty Thursday to adultery and other charges that could send him to prison for up to 15 years. His lawyers are hoping the plea will limit some of the salacious evidence and reduce the case to his word against hers.
Defense lawyers will likely ask the woman about some of the thousands of text messages she exchanged with the general, many of them sexually explicit.
Four months after she claims Sinclair sexually assaulted her, records show the captain traded a series of affectionate emails with the general. The captain signed off by saying she "owed" him, a code word defense lawyers say the paramours used as a substitute for "love."
"I hope you are doing super great and feel the positive energy I'm trying to send you way!" she wrote to her alleged abuser. "You will know it's working if you feel SUPER GREAT today!!! I will always owe you the most Sir!"
The trial is unfolding with the Pentagon under heavy pressure to confront what it has called an epidemic of rape and other sexual misconduct in the ranks. On Thursday, the Senate rejected a bill that would have stripped commanders of authority to decide whether to prosecute serious crimes.
Sinclair's accuser testified that the first assault took place in her office in Kandahar when she told him how she hated her life, hated working for him and believed the general was just using her for sex.
"He grabbed me by the back of the neck and pushed me down. I tried to pull back, and he put his other hand on my shoulder," she said. "It felt disgusting. It felt like I had no control over my body."
She said the second assault took place in his office days later after she asked him to move her to another job. She said that after that episode, they never had sex again.
Asked why she did not come forward and report what happened until March 2012, she said: "I knew if I said anything, it would be my word against his and no one would believe me. I had no way out."
She also testified in detail about how the affair developed, and said that Sinclair once threatened to kill her and her family — and "do it in a way no one would ever know" — if she ever told anyone about their relationship.
She was given immunity in exchange for her testimony. Adultery is a crime under military law.
In opening statements, prosecutor Lt. Col. Robert Stelle painted Sinclair as a man who used his authority to intimidate and coerce a female officer nearly 20 years his junior into sex.
Defense lawyers portrayed Sinclair as the victim of a desperately infatuated woman who became angry when she discovered that another woman had sent the general an email that closed with "I love you."
The defense also contends Sinclair is the target of overzealous prosecutors under political pressure to make an example of him, despite weak evidence and an accuser with a history of telling lies.