AREZZO, Italy, Nov 15 (Reuters) - An Italian prosecutor said on Thursday he would prepare a murder case against a policeman who shot dead a soccer fan last weekend and triggered riots.
Police had said the shooting on Sunday of Lazio fan Gabriele Sandri by policeman Luigi Spaccarotella had been a "tragic accident".
"It's an unforgivable act because the gun is a last resort," said chief prosecutor Ennio Di Cicco, adding there was no question that Spaccarotella fired at shoulder height.

Asked whether he would accuse Spaccarotella of murder instead of manslaughter, Di Cicco said: "It's a given".
The shooting sparked riots by hundreds of fans, who set cars on fire and attacked police barracks. The violence forced Italy, the country that took home last year's World Cup, to cancel this weekend's lower division matches.
Di Cicco said there were no plans to put Spaccarotella under preventative arrest as he posed no flight risk.
The policeman's lawyers promised a robust defence.
"We'll defend him tooth and nail," said defence lawyer Francesco Molino.
In Italy, prosecutors formulate accusations against suspects before seeking formal charges and indictments before a judge.
Spaccarotella denies he took aim at Sandri, a 26-year-old Lazio supporter, whose funeral on Wednesday drew thousands of fans and even Italian soccer stars like Francesco Totti. The shooting took place across a motorway after a scuffle between rival fans at a rest stop.
It was the second violent death linked to Italy's top league soccer this year. A policeman died in rioting outside a stadium in Sicily in February, six days after a death in a fight at an amateur club.
FANS' TRAVEL BAN
Italy's anti-hooligan body on Thursday banned six clubs' fans from travelling to their next Serie A games following Sandri's shooting.
One of Sandri's friends with him in a car at the time told an Italian daily that he saw the policeman taking aim at them with "both hands on the pistol". Then he heard a dull thud.

"When I looked in the (car) mirror, I saw Gabriele spit up blood," the friend, identified by La Repubblica newspaper as Marco, said.

Interior Minister Giuliano Amato has promised a thorough probe into the actions of the policeman.
Amato has also accused fans of using the incident as an excuse to go on the rampage around the country, for which two young Romans may face terrorism charges.
Some politicians want much tougher action than the soccer federation's suspension of second and third division games this weekend, when no top-flight domestic matches are scheduled since Italy are playing Scotland in a European championship qualifier.
Under Thursday's ban on fans' travel, AS Roma supporters will not be able to see their side face Genoa on Nov. 24 and Atalanta followers will be stopped from visiting Italian title-holders Inter Milan later that day.

AC Milan's support are barred from the European champions' trip to Cagliari on Nov. 25, when the Empoli v Torino, Livorno v Sampdoria and Napoli v Catania games will also be missing away fans. (Additional reporting by Paul Virgo in Rome; Writing by Phil Stewart; Editing by Charles Dick)

By Silvia Ognibene
www.guardian.co.uk