An English teacher at an Oklahoma high school is charged with second degree rape following an alleged inappropriate relationship with a student.

Kalyn Thompson, 25, turned herself in to police on Monday. She resigned from her position at Kellyville High School in April.

"This will follow her for the rest of her career," Creek County Detective Chrissie Underwood told NewsOn6. "She probably will not have a career in teaching after this."

Investigators say that Thompson had worked at the school for less than a year when she began texting with a 17-year-old male student in December. The text messages soon took on a sexual nature, administrators told police, and the relationship allegedly began to escalate.

In a police interview, the victim, who is in his junior year, told investigators that he had sex with Thompson twice -- once at a local lake and once at a Tulsa motel. Although the age of consent in Oklahoma is 16, Underwood said that as a teacher, Thompson is an authority figure.

"It's sad because they're vulnerable to it, and obviously he's getting a good grade from it," she told NewsOn6.

According to police, the victim was "flunking English last semester but currently has a 98 percent grade point average."

Police said the boy's mother asked the teacher not to contact her son outside of school after she discovered texts from Thompson on his phone, but the suspect persisted.

High school staff found out about the relationship in April after two other students saw Thompson in the victim's truck away from school, took photos, and reported it.

Parents were shocked to learn of the allegations.

"You send your kids to a small town school thinking they're going to get a better education, because it's more one-on-one. You don't expect to hear about a teacher messing with their student," Michael Sullivan -- who just enrolled his 14-year-old daughter at the school -- told KJRH.