The Italian policeman who fired the shot that killed a Lazio fan on Sunday has said his gun went off as he ran to stop rival supporters fighting.
The unnamed policeman, who is under investigation for manslaughter, told a newspaper he had not aimed at anyone.
Sunday's violence erupted after the shooting of Gabriele Sandri, 26, at a motorway service station near the Tuscan city of Arezzo.
The Lazio fan, from Rome, was hit by a bullet in the neck as he sat in a car while police tried to stop fighting between followers of his team and Juventus supporters.
Prosecutors have opened an inquiry into manslaughter, though Arezzo police chief Vincenzo Giacobbe said more serious charges could still be laid.
Floral tributes and football scarves were laid outside the shop owned by the family of the dead disc jockey in the Italian capital on Monday.
A note posted on the window of the premises read: "Yesterday a disgusting bastard killed my son. May you be cursed forever."
But the policeman who fired the shot told the newspaper Il Corriere della Sera it was a tragic mistake.
The officer, who has been in the force for 12 years, said he fired his pistol more than 200m (660ft) away from Mr Sandri.
The fan was sitting in a car on his way to see Lazio play Inter in Milan.
"I was not aiming anywhere, I was not pointing at anyone," the policeman was quoted by the newspaper as saying. "The first shot I fired in the air and the second went off as I was running. What a fool. Now I know what happened, I am devastated.
"Now I have destroyed two families, that of this boy and mine," he added.
An autopsy was being carried out on Mr Sandri's body on Monday.