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 Jan. 14 because defense attorneys requested more time to prepare their arguments.

The Interior Ministry decided to open an investigation after several newspapers published stories Saturday alleging cooperation between police and at least one of the suspects.

Radikal newspaper quoted two of the suspects, Abuzer Yildirim and Salih Guler, as saying in their testimonies that a third suspect Emre Gunaydin told them that he had met with police officials and learned about the locations of Christian churches in the city.

"I asked him who are the police chiefs that you are speaking to, he said: 'Don't ask, take it easy,"' Radikal quoted Yildirim as saying.

Similar allegations have also emerged after the January killing of an ethnic Armenian journalist, Hrant Dink, who was detested by hardline nationalists because he described the mass killings of Armenians in the early 20th century as genocide.

Turkey denies the deaths constituted genocide, insisting those killed were victims of civil war and unrest.

Critics have accused authorities of failing to act on reports of a plot to kill Dink but there has been no evidence that directly implicates any police or government officials in the slaying of Dink outside his office.

Many Turks are convinced that a so-called "deep state" — a network of state agents or ex-officials, possibly with links to organized crime — periodically targets reformists and other perceived enemies in the name of nationalism.

Christian leaders have said they are worried that nationalists are stoking hostility against non-Turks and non-Muslims by exploiting uncertainty over Turkey's place in the world.

The uncertainty — and growing suspicion against foreigners — has been driven by Turkey's faltering EU membership bid, a resilient Kurdish separatist movement and by increasingly vocal Islamists who see themselves — and Turkey — as locked in battle with a hostile Christian West.