The Italian policeman who allegedly killed a soccer fan was placed under investigation Nov. 12 for possible manslaughter, a day after the killing sparked riots across the country.

Authorities detained four people for taking part in the violence in Rome, where fans attacked a police barracks and the Italian Olympic Committee's headquarters. Meanwhile, sports authorities met in Rome to decide on possible measures as a response to the latest episode of soccer-related unrest.

Gabriele Sandri, a 26-year-old disc jockey from Rome, died being hit in the neck by a bullet while sitting in a car. Police said an officer fired shots to disperse a scuffle at a highway rest stop in Tuscany.

Police have called the man's death a "tragic error" and the circumstances surrounding it remain unclear. "We'll uncover the truth," Police Chief Antonio Manganelli said Nov. 12.

Officials said the policeman who fired the shot was put under investigation for possible manslaughter by magistrates in Arezzo, a Tuscan town about 200 km north of Rome where the killing occurred.

"For now he is under investigation for manslaughter," Arezzo Police Chief Vincenzo Giacobbe said.

Police intervened to stop a scuffle between groups of Lazio fans -- headed to see their club play at Inter Milan -- and a group of Juventus fans.

According to police, an officer fired two warning shots in the air. But the unidentified officer told Corriere della Sera Nov. 11 that the second shot went off accidentally.

Sandri's death forced the suspension of three matches as clashes erupted in cities, including Milan and Bergamo in the north.