Homicide

Cops: Man 'fooling around' with gun kills firefighter friend

  • Patrick Riccardi-O'Connor, left, of Stoneham, Mass., stands during arraignment Wednesday, June 29, 2016, in Woburn, Mass., District Court, on charges he fatally shot his firefighter friend David Atherton while playing with a handgun Tuesday night. Riccardi-O'Connor pleaded not guilty. (Patrick Whittemore/Boston Herald, Pool)

    Patrick Riccardi-O'Connor, left, of Stoneham, Mass., stands during arraignment Wednesday, June 29, 2016, in Woburn, Mass., District Court, on charges he fatally shot his firefighter friend David Atherton while playing with a handgun Tuesday night. Riccardi-O'Connor pleaded not guilty. (Patrick Whittemore/Boston Herald, Pool)  (The Associated Press)

  • Patrick Riccardi-O'Connor, of Stoneham, Mass., stands during arraignment Wednesday, June 29, 2016, in Woburn, Mass., District Court, on charges he fatally shot his firefighter friend David Atherton while playing with a handgun Tuesday night. Riccardi-O'Connor pleaded not guilty. (Patrick Whittemore/Boston Herald, Pool)

    Patrick Riccardi-O'Connor, of Stoneham, Mass., stands during arraignment Wednesday, June 29, 2016, in Woburn, Mass., District Court, on charges he fatally shot his firefighter friend David Atherton while playing with a handgun Tuesday night. Riccardi-O'Connor pleaded not guilty. (Patrick Whittemore/Boston Herald, Pool)  (The Associated Press)

  • Patrick Riccardi-O'Connor, right, of Stoneham, Mass., stands as his attorney Andrea Levy speaks on his behalf during his arraignment Wednesday, June 29, 2016, in Woburn, Mass., District Court, on charges he fatally shot his firefighter friend David Atherton while playing with a handgun Tuesday night. Riccardi-O'Connor pleaded not guilty. (Patrick Whittemore/Boston Herald, Pool)

    Patrick Riccardi-O'Connor, right, of Stoneham, Mass., stands as his attorney Andrea Levy speaks on his behalf during his arraignment Wednesday, June 29, 2016, in Woburn, Mass., District Court, on charges he fatally shot his firefighter friend David Atherton while playing with a handgun Tuesday night. Riccardi-O'Connor pleaded not guilty. (Patrick Whittemore/Boston Herald, Pool)  (The Associated Press)

A Massachusetts man has pleaded not guilty to charges he fatally shot his firefighter friend while playing with a handgun.

Patrick Riccardi-O'Connor was arraigned Wednesday in Woburn District Court on charges of involuntary manslaughter and related crimes.

Police found 24-year old firefighter David Atherton dead Tuesday night inside a Stoneham residence.

Police say Riccardi-O'Connor originally told them Atherton had shot himself but later admitted shooting Atherton while the two were drinking alcohol and "fooling around with the gun." Riccardi-O'Connor told police he didn't think the gun was loaded.

Prosecutors say the men were childhood friends.

Riccardi-O'Connor's attorney didn't immediately return a message seeking comment.

In a statement, Stoneham's interim town administrator recognized Atherton for his service as a town firefighter and National Guardsman.