Turkey has launched an investigation into alleged collusion between police officers and at least one of the suspects charged with killing three Christians earlier this year at a publishing house that produces Bibles, an official said Saturday. Two senior police inspectors will be assigned to investigate whether any officers provided assistance to the suspects, an Interior Ministry official said on condition of anonymity because he was not authorized to speak to the media. He did not provide further details. The three Christians - a German and two Turks - were killed in the southern city of Malatya on April 18. The killings - in which the victims were tied up and had their throats slit - drew international condemnation and added to Western concerns about whether Turkey can protect its religious minorities. Five people were arrested and charged with murder. The trial opened last month, but was quickly adjourned until January 14 because defense attorneys requested more time to prepare their arguments.