BERLIN (BBC)–German Chancellor Angela Merkel has urged Turkey to tackle "unacceptable intolerance" in the country, following the killings of three Christians. In a newspaper interview, Merkel called on the Turkish authorities to combat the "climate in which such terrible murders are possible". The Christians, one of whom was German, were found with their throats slit in south-eastern Turkey on 18 April. On Sunday four men and a woman appeared in court charged with their murder. The men, aged 19 and 20, were arrested at the office of a Christian publishing house in Malatya, the town where the deceased worked. The 18-year-old woman is accused of aiding a terrorist group, prosecutors said. The court ordered the release of six other young men, pending trial for alleged lesser roles in the murders, media reports said. Merkel, whose country holds the rotating EU presidency, told the Muenchener Merkur newspaper: "These murders are an expression of an unacceptable intolerance." The killings were seen by some observers an attack on the country’s Christian minority. Christians make up less than one percent of Turkey’s Muslim-majority population. The three victims–a German and two Turkish citizens who had converted to Christianity–were found with their hands and legs bound and their throats slit. Nationalists had protested at the publishing house in the past, accusing it of involvement in missionary activities, local media reported. Prime Minister Recep Tayyip Erdogan had vowed to bring those responsible to justice and described the attack as "savagery".