The parents of a Waldorf boy filed a lawsuit this week against a small Baptist academy in Indian Head, alleging that a school administrator who has since disappeared amid a police investigation threatened to injure their son.

The lawsuit alleges that Peter R. Ferguson, the former administrator of Potomac Heights Christian Academy, told 9-year-old student Ellis J. Burgess that he would "knock his [expletive] brains down his throat" for not addressing Ferguson as "Sir."

"Burgess was extremely scared," according to the suit, filed in Charles County Circuit Court by Upper Marlboro attorney Jimmy A. Bell on behalf of Ellis and Deborah Burgess, the boy's parents. They are seeking $5 million in damages.

If true, the allegation would be just one of several incidents that caused the school's board of directors to fire Ferguson on Nov. 7. In letters to parents explaining the firing, school officials cited "a clear and undeniable pattern of un-Christ-like behavior" and "incidents of profanity, lying and yelling at students."

A day after his dismissal, Ferguson disappeared, just before an audit would reveal that thousands of dollars were missing from a fundraising bank account, authorities said.

Detective Sgt. Randy Sweeney, of the Charles County sheriff's office, said investigators are still searching for Ferguson to question him.

Ferguson was hired by the academy in February 2001, shortly after he resigned from a boarding school in rural Oregon. The 200-student academy has served children in kindergarten through eighth grade since the 1970s.

Ellis was the only one of a group of boys to be yelled at by Ferguson on Oct. 1, according to the lawsuit. When confronted later by the boy's parents, Ferguson admitted only that he was "extremely forceful in his verbosity," the suit says.

According to the lawsuit, Potomac Heights Christian Academy officials "had prior knowledge of [Ferguson's] threatening behavior" and should have fired him long before the incident with Ellis occurred. The academy, not Ferguson, is the defendant in the lawsuit.

School officials did not return phone calls Tuesday seeking comment.