The Forsyth County Sheriff's Office is investigating a third possible case against a Jefferson Middle School math teacher who has been charged with sexual offenses involving two girls at the school. The sheriff's office is trying to retrieve about 1,000 text messages exchanged between Mark Tobin Mercer and the third girl, Maj. Brad Stanley, a spokesman for the sheriff's office, said Thursday. The content of those messages will determine whether additional criminal charges will be filed, Stanley said.

A story Thursday in the Winston-Salem Journal incorrectly reported that the 1,000 text messages were exchanged with one of the two students named in the warrants alleging 29 counts of sexual offenses. Those two students' parents went to Winston-Salem police Sunday with concerns about the nature of the girls' relationships with Mercer.

Mercer, 23, of 805 Ellington Drive, was charged Tuesday with 13 counts of statutory rape, eight counts of felony sex offense with a student and eight counts of taking indecent liberties. Police say the incidents occurred off campus between Oct. 1 and Dec. 28. Mercer was being held Thursday afternoon in the Forsyth County Jail with bond set at $1.2 million. He is scheduled to appear in court Jan. 21.

In the third case, which is being handled by the sheriff's office, the mother of the girl who exchanged the large number of texts with Mercer discovered them on her daughter's phone on Dec. 28. The parent called a Winston-Salem/Forsyth County school system administrator, who met with the parent, Jefferson Principal Brad Royal and Jefferson's school resource officer, who is a Forsyth County sheriff's deputy.

The parent could see the number of messages but could not read them, Superintendent Don Martin said. The excessive number of texts violated the system's Internet policy, which calls for minimal individual contact between teachers and students, and Martin said he advised school administrators to draft a letter suspending Mercer with pay.

After the criminal charges investigated by Winston-Salem police came to light, the school system suspended Mercer without pay. Martin said he will recommend to the school board that the teacher be fired. As of Thursday afternoon, police said they knew of no other potential cases linked to Mercer.