BOSTON — One of two Rhode Island men charged with assault and battery and disorderly conduct in connection with the death of a fan at a New England Patriots game pleaded not guilty Friday.

In a brief appearance at Wrentham District Court, John Vieira, 59, entered the plea over allegations he and Justin Mitchell, 39, punched Dale Mooney, of Newmarket, New Hampshire. Mooney, 53, was struck during an altercation at the Sept. 17 game, which ended in a 24-17 win by the visiting Miami Dolphins, investigators said. Mooney was taken to a hospital, where he was pronounced dead.

Criminal complaints filed in December said both Vieira and Mitchell, both of Warwick, Rhode Island, “did assault and beat Dale Mooney.”

A phone number for Vieira could not be found Friday.

The Office of the Chief Medical Examiner provided preliminary indications that did not suggest traumatic injury, but did identify a medical issue, according to the district attorney’s office. The cause and manner of death were undetermined at that time, pending further testing.

Final determinations delivered to the Norfolk District Attorney’s Office ruled the manner of death a homicide. The cause of death has been ruled as “probable cardiac dysrhythmia in a person with severe hypertensive and atherosclerotic cardiovascular disease during a physical altercation.”

The review of the available evidence, including the autopsy results and multiple angles of video capturing the incident, failed to establish a basis for criminal prosecution of charges related to homicide in Mooney’s death, Norfolk District Attorney Michael Morrissey said.

Gillette Stadium officials said at the time that they were “heartbroken” by the death of Mooney, who they said was a lifelong Patriots fan and 30-year season ticket holder.