SALT LAKE CITY, Utah, July 10, 2008 (NBC) -- Police have arrested a school teacher in Harrisville, Utah, in an unusual case: a texting relationship with a student that went too far.

That teacher is now in jail.

In one month alone, he sent 5,000 text messages to a 13-year-old girl.

There's no indication that the two had a physical relationship, but their text-messaging affair crossed the line between teacher and student.

"He is a young, new teacher who had been warned about texting kids and just didn't really seem to understand,” said Jean Hill, an attorney for Utah’s State Board of Education. “You have got to keep those professional boundaries pretty tight.”

Brandon Fessler went too far, texting one of his students at Orion Junior High School in Harrisville.

"His principal had talked to him about boundaries, and part of that discussion included texting with kids," Hill said.

Last summer, the victim's family got a restraining order against Fessler.

Court records say he violated it by texting or e-mailing the teenager on seven different days.

In court at Fessler's sentencing on Monday, the victim's brother-in-law read part of a poem Fessler wrote to the girl.

It said, "You taught me the poetic measure of love and the meaning of life."

The judge said he was appalled at the lurid nature of some of Fessler's messages to the girl, especially because he was in a position of trust as her teacher.

He was ordered to pay for therapy for the whole family.

In one month, the two exchanged 5,000 text messages.

That's 167 a day, or as many as 17 texts an hour during a typical work day.

The victim's mother said Fessler convinced her now 15-year-old daughter that they're in love.

"You continued to contact her after I begged you that day on the phone to leave us alone, and you still called her," she said during the court hearing.

The judge sentenced Fessler to one year in jail for two counts of misdemeanor stalking.

"I think the judge is absolutely right,” Hill said. “This is a person in a position of trust. Again, these are kids, and if you can't handle that role that you've taken on, then something does need to be done.”

Hill says more and more cases of improper teacher conduct involve text messaging. She hopes this case will be a lesson for all teachers.

"We really need teachers to remember, even though the medium is informal, you still have to establish the boundaries with your students," she said.

In court, Fessler apologized to the victim's family.

The State Board of Education revoked his teaching license for one year.

If he wants to teach again, he'll have to ask for a reinstatement
hearing.

The criminal charges will play into that decision.