SAN JOSE — After a second former student came forward with more damaging testimony against him, an ex-assistant principal at Leland High School pleaded guilty on Monday to felony and misdemeanor counts related to unlawful sexual contact with a minor, prosecutors said.

The counts against Joseph Jon Reghitto, 34, involved one felony count of penetration with a foreign object of a child under 18 and one misdemeanor count of annoying or molesting a child, said Santa Clara County prosecutor Carolyn Powell. Reghitto must now register as a sex offender.

Reghitto began exchanging numerous inappropriate text messages with a Leland High student in 2011 when she was 16 years old — contacts that eventually led to a sexual act at a park near the school in September 2011, said Powell.

“The amount of texts were mind-blowing,” said the victim’s father, who is not being identified to preserve the victim’s anonymity. “I think there were 1,300 in three weeks.”

He said he knew they existed because of phone records but does not know what the texts contained.

Last week, a judge agreed to allow testimony from another former Leland student who also had been receiving texts from Reghitto, said Powell.

“There was a senior girl from the previous year who had received similar inappropriate text messages,” Powell said. “There was no physical contact prior to her turning 18, but there is information that there was some later.”

Defense attorney Jeff Kroeber could not be reached for comment on Monday.

The allegations came to light when another student who knew about the relationship went to authorities.

Reghitto, who was arrested in May 2012, was working in his second year as assistant principal at the school, overseeing student activities and serving as adviser for the sophomore class. He was previously assistant principal at Hoover Middle School, where he also taught. He joined the district in 2004 as a teacher at Bret Harte Middle School.

The spokeswoman for San Jose Unified School District would not comment on the case on Monday.

Prosecutors said Reghitto will be sentenced early next year after a recommendation from the probation department and an evaluation by a court-appointed clinical psychologist for risk of repeat offenses. He faces a maximum penalty of three years in prison.

The victim’s father, who has attended 32 court appearances in the past 17 months, plans to be there.

“I’ll do cartwheels,” he said. “I’ve been to every court appearance so (my daughter) didn’t have to go. I wanted to make sure Reghitto knew our disdain for him will never die.”

He was “greatly relieved” when he heard about the pleas because he did not want his daughter to have to go through the trauma of a trial.

In a phone call Monday, the victim, who is now 19, said she’s glad to put the matter behind her.

“I’m relieved, but I wasn’t necessarily nervous about the trial,” said the victim, who is in counseling. “It was an ongoing process that seemed like it would never end. I don’t like seeing him.”

She said the counseling has “definitely helped.”

“Mentally I’m great,” she said. “The court part was the last thing to finally go.”

Her father said Reghitto “shattered a lot of lives.” Both he and his daughter believe he may have victimized other students.

“He was in a position of trust, a position that people go to for help and that’s exactly how this relationship started,” he said. “To take advantage of that, it’s devastating to any student.”

Staff writer Tracey Kaplan contributed to this report. Contact Eric Kurhi at 408-920-5852. Follow him at Twitter.com/erickurhi.