James Hooker, 41, insisted that his relationship with Jordan Powers became sexual only after she turned 18. She was his student at Enochs High School. Powers' mother suspected otherwise, which sparked a police investigation.
In the course of the investigation, detectives say they found evidence that Hooker had sexually assaulted a 17-year-old student in 1998. He was taken into custody for investigation of oral copulation with a minor.
Hooker appeared in court on Friday, where a judge set his bail at $50,000 and assigned him a public defender.
Police allege that in this incident, Hooker developed a romantic relationship with a minor when he was a teacher at Davis High School, which is also in Modesto.
Police continue to investigate his relationship with Powers.
In response to the couple's relationship, a state lawmaker from Modesto last week proposed legislation that would ban student-teacher relationships regardless of age, even if the student is 18, and strip school employees of their pensions and retiree health care if they are convicted.
The Associated Press contributed to this report.