The asphyxiation death of a former Gallaudet University student last week after a struggle with campus police was caused by pressure on his neck, a District police source said yesterday.

The source said the D.C. medical examiner's autopsy report on Carl Dupree, 41, of Springfield, indicated injuries that may have been caused by a choke hold or by pressure applied with a nightstick or similar object.

Dupree's death has been ruled a homicide, meaning that it was caused by another person. The case is being referred to the U.S. Attorney's Office.

Police said Tuesday that the medical examiner's findings showed that Dupree died of asphyxiation, but they provided no details.

Yesterday, a police source said the autopsy report attributed Dupree's death to asphyxiation by neck compression, which apparently broke his hyoid bone. The hyoid, a crescent-shaped bone about 1 1/2 inches across, lies between the root of the tongue and the larynx.

The police source said that a choke hold sometimes can break the bone, as can pressure from a rigid object such as a flashlight or nightstick.

It is difficult for an individual to apply enough pressure to break his own hyoid bone, the source said.

Dupree collapsed on the Gallaudet campus Friday after a struggle with campus security officers followed what the university described as a "grade dispute" with an instructor. During that struggle, Dupree was restrained by at least five security officers and was handcuffed.

Since the death, some students have criticized the actions of the security officers, complaining that they used excessive force. The students also contended that handcuffing Dupree, who was deaf, deprived him of the ability to communicate in sign language.

Gallaudet, the nation's premier university for the deaf, has retained a law firm to conduct an investigation of the incident. That inquiry began Tuesday.

About 30 security officers are assigned to Gallaudet's campus in Northeast Washington. Minimum requirements for becoming a member of the force include three years of law enforcement experience, which may include prior work as a security officer.

Campus officials said the officers receive a seven-week training course and are required in their first year to take two courses in sign language.

Dupree's death has spurred expressions of concern on the campus and has aroused new interest in what one student leader called a longstanding issue: the need for teachers, administrators and security officers to be fluent in sign language. Staff writer Molly Sinclair contributed to this report.