Detectives who began investigating the case immediately after the parent's complaint found that Farrell continued corresponding with the victim via social media. He arranged to meet her at Paly on the evening of June 15. Detectives were there to meet him instead and took him into custody without incident, police said in a statement.

Farrell allegedly led the victim to his classroom, where the two of them were alone. After conversing with the girl, Farrell allegedly put his hands under the victim's clothes and touched her breasts. He also allegedly took one of her hands and placed it on his groin over his clothing. He eventually told the victim to leave the classroom, police said.

An investigation revealed that teacher Ronnie Farrell, 46, of Palo Alto, had been communicating with the victim using social media. He asked the victim to meet him at Paly on Tuesday, June 7, at 9 a.m. The victim regularly helped her teachers with chores in the classroom, and she agreed to meet him, police said.

Palo Alto police received a call on Monday, June 13, at about 8:44 p.m. from a parent who said their 15-year-old daughter had been assaulted by a teacher. The victim had recently completed ninth grade at Paly, and the suspect had been her biology teacher during her freshman year, which ended on June 2, according to police.

Palo Alto High School teacher Ronnie Farrell loads sandbags to line in front of his Community Center home in preparation for a large storm that hit Palo Alto in December 2014. Farrell was arrested on Wednesday, June 15, 2016, for alleged sex crimes with a female student. Photo by Veronica Weber.

"I am really appreciative that they reached out to us so quickly and in such detail," McGee said.

District officials learned of the allegations and of Farrell's arrest on Wednesday evening after being notified by police, Superintendent Max McGee said. Police Chief Dennis Burns called McGee a few times as the incident unfolded.

Farrell is a full-time employee of the Palo Alto Unified School District. He has taught biology and chemistry at Paly since 2012, according to the district, and was made a permanent staff member in the 2014-15 school year. Paly was his first teaching job, according to the district's communications coordinator, Jorge Quintana. Quintana said he believed Farrell "transitioned from the private sector." Quintana later said he had been a senior network administrator with Rockefeller Group Telecommunications Services in New York.

Farrell was booked into the Santa Clara County Main Jail for four felony charges: child molestation, sexual battery, communicating with a minor with the intent to commit a sex crime, and arranging a meeting with a minor with the intent to commit a sex crime.

McGee said the district has not received any previous complaints about Farrell nor any indication that he engaged in this kind of behavior.

The district is immediately putting Farrell on compulsory unpaid leave, McGee said, and will be consulting with an attorney about "any further action that we can legally (take)."

Anyone who believes that their child may be a victim is asked to call the police department's 24-hour dispatch center at 650-329-2413. Anyone with information about this incident is also asked to call the dispatch center. Anonymous tips can be emailed to [email protected] or sent by text message or voice mail to 650-383-8984.

"An eraser in Scotland is called a rubber, and I asked my teacher for a rubber in front of the class -- and that was pretty awkward. The whole class kind of just gasped and I was like, 'I made a mistake. I need a rubber,' and that didn't help. And eventually, I figured that out and I never asked for a rubber again, at least from a teacher," he said.

Farrell continued his interview in a lighthearted vein. He said that his most awkward moment as a teen student was his first or second day of high school in America.

Farrell described his own teen years during that interview. When asked what advice he would give to his teen self, Farrell was quoted as saying: "Who needs girls? You know? If there was one thing that was rough for me in high school it was I don't think one girl ever looked at me. I think one who was blind actually turned away. It was pretty bad. So if I was to give myself some advice it would be, 'You know what, Ronnie? You're going to do alright in your 20s. Hang in there, buddy. Hang in there.'"

Farrell has a wife and two daughters, according to his Facebook page. He emigrated to the U.S. from Scotland as a teenager, according to an Oct. 11, 2015, profile in Paly's student magazine , Verde.

She urged parents to "create time and a safe space for our children, especially those who had Mr. Farrell as a teacher, to process and discuss their feelings," particularly given the fact that school is out of session. She said grade-level counselors are available to help students who might need support returning to Paly, and pointed parents to an online list of counseling and crisis resources.

Noting that Farrell is a "well-liked and respected" teacher, Diorio encouraged students to "reach out to your parents, relatives, friends and/or other members of your support network over the coming months, and know that the safety of our students will always remain our number one priority."

"Like you, I was shocked and deeply saddened to first learn of this news," she wrote. "I'm at a loss for words except to say how incredibly saddened I am."

"What's most important is the well-being of this young lady. I trust that she'll have the support and help of (her) family and certainly of our whole school community," McGee said.

Palo Alto teacher arrested for alleged sex crimes

Paly biology teacher suspected of assaulting 15-year-old student