CHICAGO (WLS) -- A former JROTC instructor at a Chicago high school is facing charges for sexually assaulting a student multiple times.Brian Travis, a retired U.S. Army soldier and former Junior Reserve Officers' Training Corps instructor, is being held without bail for criminal sexual assault with a former student. The 46-year-old was arrested trying to board a flight to Mexico on Christmas Day.Prosecutors said the assault began in January and at least one of the encounters occurred inside Roosevelt High School in the Albany Park neighborhood, where he taught.When rumors of the assault surfaced, Travis was fired from his job, according to prosecutors.Prosecutors claim Travis and the victim met at Roosevelt High School and their relationship started after the 46-year-old began texting her."The victim would confide in the defendant on subjects concerning her health and her relationships," Cook County Assistant State's Attorney James Murphy said. "The defendant asked the victim if she wanted to be a sugar baby and if she wanted him to be her sugar daddy."Travis, an Indiana resident, joined the victim's gym in Chicago on North Elston to work out with her, and allegedly reserved a private massage room where their first sexual encounter took place.At the time, the victim was age 16."The defendant performed these actions with the victim at the gym, inside the defendant's office at the high school, in the defendant's cars and in a hotel room," Murphy said.Hundreds of pages of text messages between the two are now part of the investigation."In the conversations, the defendant mentions on multiple occasions that he intended to move to Mexico and marry the victim," Murphy said.Their relationship ended last month.On November 30, Travis allegedly sent text messages to the victim threatening to kill her, her parents and her friends, blaming the victim for losing his job.When Travis was arrested at O'Hare on Wednesday, the defendant claimed he was not trying to flee police but rather that he was going to Mexico with one of his two children.Travis' next court appearance is scheduled for next year.