An Erath County jury heard opening arguments Wednesday in the trial of Samuel David Lewis, 25, accused of having sex with a 14-year-old female that he trained at BQuick Brazilian Jiu Jitsu.
Lewis was arrested in January 2014 and charged with sexual assault of a child, a second degree felony.
The victim, now 17, told jurors Wednesday that she began training with Lewis in the summer of 2013. She said Lewis told her he was unhappy in his marriage.
"I being the emotional teenager, came to feel bad for him," she said. "I felt bad and was sympathetic towards him."
She said the two communicated through text messages and Facebook, and that the relationship turned sexual on Christmas Eve 2013 when they had sex in the bathroom inside the gym.
The victim's mother learned about the relationship after finding Facebook exchanges and after confronting her about their relationship, went to the police.
The victim testified that Lewis knew she was a high school freshman at the time.
Testimony will continue this afternoon.