BERLIN — German prosecutors said Wednesday that they have detained a Tunisian man they think may have been involved in last week's truck attack on a Christmas market in Berlin.The 40-year-old, who wasn't identified, was detained in Berlin during a search of his home and business, federal prosecutors said.The man's telephone number was saved in the cellphone of Anis Amri, a fellow Tunisian believed to have driven a truck into the market on Dec. 19. Amri, 24, was killed in a shootout with Italian police in a suburb of Milan early Friday.Of the new suspect, prosecutors said in a statement that "further investigations indicate that he may have been involved in the attack."Twelve people died and dozens more were injured in the truck attack. The Islamic State group has claimed responsibility.Prosecutors have until Thursday evening to determine whether the case against the 40-year-old is strong enough for them to seek a formal arrest warrant.