Istanbul governor Muammer Guler said three people were arrested in connection with the murder of journalist Hrant Dink earlier on Friday, CNN-Turk television reported.
No further information was provided on the arrests. Earlier in the day, two people were arrested, only to be released when officials decided they had no connection to the crime. Dink was one of the most prominent voices of Turkey's Armenian community, and a frequent target of nationalist anger.
Dink faced constant threats and legal proceedings as one of the most prominent voices of Turkey's shrinking Armenian community was shot to death Friday at the entrance to his newspaper's offices, police said.
Dink, a 53-year-old Turkish citizen of Armenian descent, had gone on trial numerous times for speaking out about the mass killings of Armenians by Turks at the beginning of the 20th century. He had also received threats from nationalists, who viewed him as a traitor.
Dink, who edited the bilingual Turkish-Armenian newspaper Agos, said in his last column on Jan. 10 that he had become famous as an enemy of Turks and had received no protection from authorities despite his numerous complaints about the threats against him.
"My computer's memory is loaded with sentences full of hatred and threats," Dink wrote. "I am just like a pigeon. ... I look around to my left and right, in front and behind me as much as it does. My head is just as active."
He ended the column by predicting this would be a difficult year, but he would survive it. "For me, 2007 is likely to be a hard year. The trials will continue, new ones will be started. Who knows what other injustices I will be up against," he wrote.
Dink's killing drew condemnation from Europe, Armenia, the United States and numerous media freedom and human rights organizations. Thousands of Turks marched down the street where he died, blocking traffic and carrying posters bearing his photo.
In October 2005, Dink was convicted of trying to influence the judiciary after Agos ran stories criticizing a law making it a crime to insult Turkey, the Turkish government or the Turkish national character. He was given a six-month suspended sentence.
The conviction was rare even in a country where trials of journalists, academics and writers have become common. Most of the cases, including that of the Nobel Prize-winning novelist Orhan Pamuk, were either dropped on a technicality or led to acquittals.
Prime Minister Recep Tayyip Erdogan condemned Dink's death as an attack against Turkey's unity and promised to catch those responsible. He said he had appointed top officials from the Justice and Security ministries to investigate the killing.
"Once again, dark hands have chosen our country and spilled blood in Istanbul to achieve their dark goals," Erdogan said.
Dink cried during an interview with The Associated Press last year as he talked about some of his countrymen's hatred for him, saying he could not stay in a country where he was unwanted.
"I'm living together with Turks in this country," Dink told the AP. "I don't think I could live with an identity of having insulted them in this country ... if I am unable to come up with a positive result, it will be honorable for me to leave this country."
The New York-based Committee to Protect Journalists said 18 Turkish journalists have been killed for their work in the past 18 years.
"Like dozens of other Turkish journalists, Dink has faced political persecution for his work and now appears to have paid the ultimate price for it," CPJ Middle East Program Coordinator Joel Campagna said. "Turkish authorities must ensure that this crime, like past ones, does not go unpunished."
Two people detained in the killing were later released because they had no relationship to the crime, news reports said.
Turkey's relationship with its Armenian community is fraught with tension and painful memories of a brutal past. Much of Turkey's once-sizeable Armenian population was killed or driven out of the country from 1915-1923 in what an increasing number of countries are recognizing as the first genocide of the 20th century.
Turkey acknowledges that large numbers of Armenians died but vehemently denies it was genocide, saying the overall figure is inflated and the deaths occurred in the civil unrest during the collapse of the Ottoman Empire.
Turkey, which is overwhelmingly Muslim, and Armenia, which claims to be the first country to official adopt Christianity, share a border, but it is closed and the two countries have no formal diplomatic relations.
Can Dundar, Dink's friend and fellow journalist, said he wished Dink had left the country as he once promised he would in the face of the threats, protests and legal proceedings against him.
"Hrant's body is lying on the ground as if those bullets were fired at Turkey," Dundar told private NTV television.
Dink's body was covered with a white sheet in front of the newspaper's entrance. NTV said four empty shell casings were found on the ground and that he was killed by two bullets to the head.
Workers at the newspaper, including Dink's brother, who has also been put on trial in Turkey, wept and consoled each other near his body.
Fehmi Koru, a columnist at the Yeni Safak newspaper, said Dink's slaying was aimed at destabilizing Turkey. "His loss is the loss of Turkey," Koru said.
Dink had complained in a letter that he received no responses even after complaining to authorities about threats of violence made to him, NTV reported.
A colleague at Dink's newspaper, Aydin Engin, said Dink had attributed the threats to elements in the "deep state," a Turkish term that implies shadowy, deeply nationalist and powerful elements in the government.