"He was in Singapore, so it shows he had a rapport with those others, " said Mr. Di Martino, who is based in Cremona, a town southeast of Milan.

WSJ: Suspect Surrenders in Soccer Probe

"We'll find out why, when I interrogate in the coming days, " public prosecutor Roberto Di Martino said in a telephone interview.

WSJ: Suspect Surrenders in Soccer Probe

Mr. Suljic, who will turn 32 on Saturday, had been wanted by Mr. Di Martino on suspicion of belonging to a criminal syndicate dedicated to committing fraud in sports Italian professional soccer matches in particular.

WSJ: Suspect Surrenders in Soccer Probe