FORT WORTH -- The first text message that "Aaron" received from his English teacher seemed innocent enough.
"Hey ... It's Coach Colleps. Do you know what time the baseball game starts?"
Before 24 hours had passed, the subject matter of numerous texts exchanged between Aaron and Brittni Colleps took a dramatic turn. Colleps discussed the number of her sexual partners (eight guys, two girls), her favorite sex toys and described herself as an "anything goes in sex kind of girl."
Aaron's testimony about the texts and the sexual trysts that prosecutors say followed came in the first day of testimony in the trial of Colleps, who is accused of having sex with Aaron and four other students while she was a teacher and coach at Kennedale High School.
The students were 18 or older at the time. They are using pseudonyms in court.
If convicted, Colleps, a 28-year-old married mother of three, could be sentenced to the maximum 20 years in prison and a $10,000 fine on each of five charges of an improper relationship between an educator and student.
Colleps stood without speaking when asked by state District Judge Ruben Gonzalez how she pleaded, causing the judge to enter her plea as "not guilty." Her attorney, Lex Johnston, did not give an opening statement Tuesday.
Aaron, now 20, testified that he had sexual intercourse with Colleps five times in the spring of 2011, four of which involved group sex with other male students.
Jurors were shown a graphic cellphone video of the last encounter, which Aaron testified showed Colleps having sex with Aaron and three other students. The video, taken on Aaron's phone by another student, did not show Colleps' face. It showed a woman's back as she was having intercourse with at least two different students while the others were in the room.
Shown to reporters after the trial adjourned for the day, the video occasionally panned the faces of the students as they laughed, smiled and made hand gestures for the camera.
Aaron testified that the woman in the video was Colleps, pointing out a distinctive tattoo on her lower back.
He said that Colleps had remarked, "Don't put the light in my eyes" as the other student, "Jordan," began filming.
Johnston objected to the admission of the video as evidence, arguing that it was illegally made because Colleps was unaware she was being videotaped and had not given her consent.
Gonzalez overruled Johnston's objection.
'Work some magic'
A second former student -- "Mark Wall" -- testified that Aaron had asked him to hook him up with Colleps after Mark confided that he had had sex with Colleps.
"Work some magic," Aaron had texted Mark.
Mark testified that he began exchanging e-mails, and later texts and phone calls, with Colleps in April 2011 after he initially "poked" her on Facebook and she poked back. He said the topic soon turned sexual, and the two eventually made plans to have sex.
Mark paused occasionally, seemingly embarrassed, as he testified that Colleps picked him up near his house and drove him to her house, where they had sex two days in a row. After that, he said, he got back together with a girlfriend and did not have sex with Colleps again.
Both Mark and Aaron testified that Colleps told them not to tell anyone about their encounters or she would get in trouble and lose her teacher's certificate.
Aaron testified that in an initial text exchange, before they had sex, Colleps said she couldn't send him a picture of her in lingerie because she was "not trying to go to jail."
Aaron said he replied that she couldn't go to jail because he was 19. He said Colleps replied that even if she didn't go to jail, "You are still my student" and that she would lose her teaching certificate.
Nevertheless, Aaron testified, Colleps later modeled lingerie for him and other students at her house before engaging in group sex in an upstairs bedroom. He testified that Colleps later texted him nude pictures of herself and a video in which she was using a sex toy.
Colleps' husband is in the military and was stationed at Fort Polk, La., during the time in question. Aaron testified that Colleps' three young children were not at home when he was there.
Colleps' husband previously has stated publicly that he stands by his wife. He was not in the courtroom Tuesday because he is a potential witness in the case.
In opening arguments Tuesday morning, Elizabeth Beach, who is prosecuting the case with Tim Rodgers, said word spread about the sexual encounters to other students, one of whom told their mother, a school employee.
Kennedale High Principal Rita Whatley, the state's first witness, testified that upon learning of a possibly inappropriate relationship, school officials met on May 11, 2011, first with Aaron and then with Colleps.
Colleps initially denied having inappropriate relations with the student, but text messages from her cellphone number were found on the student's phone, Whatley said.
Colleps was immediately suspended and later resigned, Whatley said.
The trial is scheduled to resume Thursday morning in 432nd District Court.