The relationship outside the classroom began over the phone, using a messenger app popular with teenagers called Kik.

She was a 15-year-old and he was her middle school speech teacher at Euless Junior High in Euless, Texas.

The pair sent messages to one another nearly every day over Christmas break, according to an arrest warrant affidavit cited by ABC affiliate WFAA. By February, they were seeing each other outside of school and engaging in a physical relationship, the victim would later tell police.

The relationship continued to escalate, and on June 2 the teenager contacted her former teacher - identified by police as 26-year-old Cornelis Smith - and told him she thought she was pregnant.

Police said the pregnancy was later confirmed using a home pregnancy test, according to WFAA.

The affidavit cited by WFAA says Smith told the teenager he would "help her if she was going to have the child or have an abortion," but "he would have to take his wife and child to East Texas first."

Eventually, the affidavit says, the teenager told her parents about the pregnancy and Smith called the family and confirmed that the unborn child was his, the station reported.

Last month, the Fort Worth Star-Telegram reported, Smith showed up at the Euless Police Department with the victim's mother, father and aunt.

He agreed to be interviewed, according to an arrest warrant affidavit cited by the paper, and told a detective that he had briefly had sex with the teenager in the parking lot of a vacant store the month before. He said he had not used a condom but didn't think he'd ejaculated, the affidavit noted.

Smith's former student told a different story. According to the affidavit, she told police that their relationship had become sexual months before. She said Smith would email another teacher so that the teenager could get permission to spend time his classroom during his conference period, the paper reported. In addition to kissing and talking about oral sex, the teenager performed oral sex on Smith, she told police.

On multiple occasions during spring break, she told police, Smith came to her parent's home and the two had sex. She noted that Smith told her he had used a condom at the time.

The Star-Telegram reported that the girl emphasized to police that "she did agree to have sex" with Smith.

The affidavit states that police were able to recover messages on the teenager's cellphone that confirmed her story, the paper reported. By the time her family met with police, the affidavit states, her stepfather told investigators that his daughter had been to a clinic on June 13 and confirmed that she was eight weeks pregnant.

Records cited by the Star-Telegram reveal that smith turned himself in to police last month. He has been charged with sexual assault of a child under age 17 and was released on $75,000 bail.

Hurst-Euless-Bedford school district officials told the paper that Smith was a first-year teacher who was "thoroughly vetted prior to his employment, and had no offenses on his record."

A district spokesman told the paper that he resigned from his position when it became clear that the district was beginning termination proceedings.

School officials said Euless police notified them that they were investigating a complaint that Smith was having an inappropriate relationship with a student.