A Mount Rainier man was charged yesterday with sending bomb threats and racist messages via e-mail to Prince George's County School Superintendent Iris T. Metts, according to police and court records.

Mark Steven Hoffman, 30, of the 3400 block of Taylor Street, was arrested Friday afternoon by Prince George's police while he was sitting at a computer terminal on the University of Maryland campus in College Park, police said.

After several hours of interrogation at police headquarters in Palmer Park, Hoffman was charged early yesterday with two counts of making false statements about a destructive device and two counts of electronic-mail harassment, police said. He was being held without bond in the Prince George's jail.

According to charging documents filed in the case, Hoffman sent an e-mail message to Metts's office Dec. 8, warning that a school would be "blown up" two days later. Tuesday, he allegedly followed up with a second message, in which he warned that a bomb would go off at another school Friday, court records state. The e-mail did not name the targeted schools, and no bomb was found, police said.

School district officials notified Prince George's police about the threats last week. On Wednesday, detectives from the police department's Computer Forensic Unit traced the e-mail to a University of Maryland computer, where Hoffman was arrested about 4 p.m. Friday while he was typing on the keyboard.

Police declined to say where on campus the computer was located. They said Hoffman is not a university employee and is not enrolled as a student.

Police also declined to disclose what Hoffman allegedly wrote in the e-mail. But a statement of probable cause filed by the arresting officer in Prince George's District Court states that the messages included "racial comments" directed at Metts.

Investigators have questioned Hoffman about other racist e-mail and letters that were sent anonymously this fall to the editor of a black student newspaper and other black campus leaders at the university. But police said they do not believe that Hoffman was involved in those incidents.

"There does not appear to be a link at this time," said Cpl. Joe Merkel, a police spokesman.

Hoffman is scheduled to appear in Prince George's District Court tomorrow for a mental competency hearing, court records show.