A longtime employee of the Hockaday School has been charged with two counts of attempting to solicit a minor online.

Bill Catterson

Bill Catterson, 61, was arrested Tuesday afternoon at the preparatory school at 11600 Welch Road in Dallas. He left the Dallas County Jail on Wednesday after posting $40,000 bail.

Eric Devlin, an assistant district attorney in Harris County, where the warrant was issued, said Mr. Catterson was chatting online with a sheriff's deputy posing as a 13-year-old when Dallas police entered his office at the school.

"They walked into the office and told him to remove his hands from the keyboard," Mr. Devlin said. "He always chatted from school. We never caught him chatting from any other location."

Mr. Catterson was director of the girls' school's audiovisual services and had worked there for 25 years, school officials said in a prepared statement.

"The school took immediate action, and he is no longer employed at the school," the statement said. "His keys and all access to the school's systems and campus have been revoked, and his computer has been taken by the FBI."

School officials said they had no reason to believe that Hockaday students were involved.

Authorities moved quickly to arrest Mr. Catterson when they realized the e-mail address he had given in chats was associated with the school, Mr. Devlin said.