The mother of a Hamden man who died after being zapped by a police stun gun last spring has sued the Hamden Police Department and one of its officers in federal court, alleging that her son’s death was the result of police brutality.

David Mills, 26, was shot with a Taser in April after he punched, kicked and bit officers who were attempting to detain him for fighting with another man, the police said.

He was pronounced dead at Yale-New Haven Hospital about an hour after the incident, raising questions about the safety of stun guns just as the New Haven Police Department was preparing to arm its officers with the guns.

Mills’ mother, Judith Ireland, accused the Hamden Police Department of inadequately training Sgt. William Sikorsky, who subdued Mills with the stun gun. As a result of his lack of training, the lawsuit alleges, Sikorsky used “unreasonable force” on Mills, in violation of the Fourth Amendment, and ultimately caused his death.

The state medical examiner’s office found otherwise. Mills, who told police he was on angel dust at the time of the incident, died of PCP intoxication and “excited delirium,” an agitated condition in which the body goes haywire, the medical examiner ruled over the summer. The medical examiner ruled the death was accidental.

The Hamden police chief, Thomas J. Wydra, declined to comment on the lawsuit. But this summer, two investigations into Mills’ death exonerated police of any wrongdoing, police said at the time. The New Haven State’s Attorney reviewed the incident and said the level of force used by police was accepatable given the circumstances.

Despite the questions surrounding Mills’ death, the NHPD handed out stun guns to officers in July. The city purchased 50 stun guns earlier this year in a pilot program that was proposed by the city’s Deadly Force Task Force last fall and approved by the Board of Aldermen.

Ireland’s civil lawsuit was filed in U.S. District Court on Nov. 14.

-Thomas Kaplan

-The Associated Press contributed reporting