The guilty plea by Jonathan Sammartino, 36, took place before San Diego Superior Court Judge Charles Rogers who heard the preliminary hearing in January.
He pleaded guilty to a felony count of engaging in unlawful sexual intercourse with a minor when he had sex with her in 2016. Two other sex counts were dismissed after he pleaded guilty to one count.
Sammartino faces a maximum term of three years in prison and a $10,000 fine, but he is more likely to be placed on probation with up to a year in jail, according to Rogers.
With the guilty plea, Sammartino agreed not to apply for a teaching credential or work as a teacher. He worked for a private school in San Jose at the time of his 2018 arrest and he is no longer there.
Rogers said in court he was "not inclined" to order Sammartino to register as a sex offender. But if he changes his mind, Sammartino might have to register as a sex offender for life in whatever community he lives in. He was married at the time but is now divorced.
Sentencing was set for Oct. 21. Sammartino remains free on a $25,000 bond. His mother is U.S. District Court Judge Janis Sammartino, who attended the two-day preliminary hearing.
His attorney, Eugene Iredale, has argued that Sammartino suffered brain damages in 2015 when he fell from a bicycle and injured his head in three places. Sammartino struck a pothole on Torrey Pines Road and people who knew him said that changed him substantially, according to testimony.
Iredale said that the accident limited his ability to relate, plan, or control his conduct. A longtime friend testified in January that the accident changed him so much that he needed constant reminders of when to eat meals or do errands.
Deputy District Attorney Martin Doyle said Sammartino violated a position of trust as there is "a reasonable expectation" that teachers do not have sex with students.
The hearing Aug. 27 was held in a mostly closed courthouse in which Sammartino appeared on a video screen and the two lawyers also appeared remotely. Audio from the hearing was live-streamed online.
The female student first reported sexual incidents while she was in college in 2018. She testified that Sammartino sometimes picked her up outside her home. She said they engaged in sexual relations in his home and car.
Iredale said his client believed the girl was 18 years old at the time. Sammartino has a doctorate in experimental psychology.