A 46-year-old school janitor sodomized a 10-year-old girl and then threatened to stab her in the heart if she told, according to an arrest affidavit.

Charleston County sheriff's detectives arrested West Ashley resident Kirby Wright on a charge of first-degree criminal sexual conduct with a minor Monday afternoon.

He appeared in bond court Tuesday, but a magistrate judge could not set bail on the charge. A circuit judge must set bail for a crime that carries a possible life sentence.

Officials said Wright attacked the girl, the daughter of a friend, at his home on Dupont Road sometime between June and August 2010. The girl eventually told her mother about the alleged assault, and her mother took the girl to the Dee Norton Lowcountry Children's Center for a medical exam.

Wright worked as a day porter at Garrett Academy of Technology. Sheriff's officials said they have no evidence to suggest that he made inappropriate contact with any students.

The girl told an interviewer at the Lowcountry Children's Center that Wright had been baby-sitting her and told her he wanted to show her his daughter's dollhouse, according to the affidavit. He led her into his bedroom and pushed her onto the bed, where he rubbed himself on her, the girl told the interviewer.

Wright then made the girl get down on the floor and sodomized her, according to the warrant report. When she began to cry, he "told her to hush and not to tell or he would stab her in the heart," the girl told the interviewer.

Wright previously worked for the Charleston County School District but last year began working for GCA Services Group at Garrett Academy.

Officials said he no longer works in Charleston County School District schools.

Reach Allyson Bird at 937-5594 or on Twitter at @allysonjbird.