A math teacher in Texas was arrested this week for allegedly sexually assaulting a teen on his birthday nearly 20 years ago, police said.

Gregory Peters, 51, was arrested Wednesday after the purported victim – who was then 16 years old – told police she performed a sex act on him on the night of his birthday in March 1999, the Fort Worth Star-Telegram reports.

Peters admitted that he tutored the girl, as well as tickling her and her friend, before letting them spend the night at his home while he was a 33-year-old teacher and coach at a high school in the Kennedale school district. But Peters denied having oral sex with the girl, according to an arrest warrant obtained by the newspaper.

“We are not certain why she came forward now but it’s not uncommon for someone to report this type of offense years later,” Arlington police Lt. Christopher Cook wrote in an email.

Peters, who is now facing charges of sexually assaulting a child under 17, has since been placed on leave from his position at Arlington Martin High School, school officials confirmed.

“He was removed from campus,” school spokeswoman Leslie Birdow told the newspaper. “He was reported to the Texas Education Agency after the AISD was made aware of his arrest. Peters was not an AISD employee when this incident occurred. When Peters was hired in 2012, there were no issues in his background that would have indicated any concerns.”

The alleged victim and her friend first came into contact with Peters after they started prank-calling him while they were sophomores in high school, according to the arrest warrant. Peters then told the girls he wanted to meet them, prompting the teens to go to his home in Arlington.

After volunteering to tutor them in math, Peters had the girls play with his dog, wash his hair and paint his fingernails. He also allowed them to sleep in a guest bedroom, according to the warrant.

A witness told police on Monday that she was Peters’ neighbor at the time and remembered the girls’ visiting his home several times. Peters also invited the witness to his home, but the woman declined because she didn’t “like the way [Peters] looked at or talked to her,” saying he seemed “creepy” to her, the warrant states.

One of the girls stopped going to Peters’ home after meeting a boyfriend, but the alleged victim continued visiting him, including one occasion on March 19, 1999, when Peters took her out to dinner and introduced her to his brother. He also took the girl into a hot tub at an apartment complex in Arlington before heading to his home, according to the warrant.

Peters, who has been released from custody after posting $5,000 bond, declined to comment when reached by the Star-Telegram on Thursday. Investigators have not ruled out the possibility that Peters victimized other girls, the newspaper reports.

Peters most recently taught Advanced Placement math courses at Arlington Martin High School, according to a cached website cited by KXAS. Prior to teaching, Peters graduated from Texas A&M University with a degree in political science.