Baghdad, Sep 1 : The Iraqi judiciary has sentenced an Iranian citizen and four Iraqi nationals to life imprisonment for killing a US citizen in Baghdad last year, the country's Interior Ministry said in a statement. The American, identified as Stephen Troll, was shot dead by a group of armed kidnappers while driving with his family in central Baghdad last November, Xinhua news agency reported. The attackers were later arrested and prosecuted after they confessed to committing the crime, said the statement issued on Thursday. It added that the intelligence team is still looking for four other suspects. According to media reports, Troll, once an English teacher in Baghdad, was also a member of a relief organization affiliated with the United States Agency for International Development. The statement stressed that the Iraqi security forces are capable of maintaining the country's security and stability and providing protection for citizens of all nationalities living in the country. /IANS