A Ridge Community High School teacher faces charges after investigators say he had numerous sexually-explicit conversations with one of his former students.

Dale Pennington, 36, made his first appearance Thursday. He was arrested for allegedly having an "inappropriate relationship" that detectives said was first reported by a "confidential source" in a phone call to the sheriff's office.

Polk County Sheriff Grady Judd said Pennington sent e-mails, sexually explicit text messages and pornography to the 16-year-old girl.

According to detectives, the person reported they found "inappropriate email and text conversations between Pennington and a 16-year-old girl he taught during the 2011-2012 school year at the school."

Detectives who interviewed Pennington said he admitted that since May 2012, he had been emailing and texting a 16-year-old world history student he taught; the girl is not a student of his this school year, officials said.

The relationship started back in May 2012 and continued until about a week ago. Judd said Pennington willingly admitted his actions to investigators.

Prior to these charges, officials say Pennington's record was clean. However, Sheriff Judd believes Pennington did not just start this behavior and that there may be more victims.

According to the affidavit, the conversations between Pennington and the victim were extremely sexually explicit. Investigators say Pennington sent her adult pornography via email and nude photos of himself, and that she sent semi-nude photos of herself.

He discussed wanting to have sex with her on several occasions but the sheriff does not believe they ever did.

"I can tell you that if he was doing that with my 16-year-old daughter, the safest place he could be is in the county jail where he's locked away from me," Judd said. "I mean you just don't talk to my daughter like that and not have some repercussions if it was on the street.  I mean, that's your baby girl."

Judd is asking parents to talk to their children to see if they have any information about possible victims or if they might be a victim themselves. He urges anyone with information to come forward and promises their identities will remain confidential.

Judd said Pennington is married and that his wife is outraged and had no idea about her husband's actions.

Pennington has been charged with 15 counts of use of a computer to seduce a child, 16 counts of transmission of material harmful to minors by electronic device, computer pornography - traveling to meet a minor, and 15 counts of unlawful use of a two-way communication device.  A judge set his bond at $5,000.

Detectives are investigating to determine if Pennington committed any other crimes against any other children. They have also seized his computers and phones, and further charges are pending the investigation.