The men, who the authorities said were arrested on Wednesday, ranged in age from 19 to 27; six of them are Moroccan, one is Algerian and one has dual Moroccan and Spanish citizenship.
Officials said the main suspect, who was arrested on Tuesday and also has not been identified, had ties to Islamic militants and had visited the apartments of the eight men.
Van Gogh, a grandson of the painter Vincent van Gogh’s brother, Theo, was an outspoken opponent of Islamic extremism and recently had received death threats after the broadcast of a short film called “Submission,” which criticized mistreatment of Muslim women.
He was shot and stabbed on an Amsterdam street early Tuesday. The main suspect, who holds Dutch and Moroccan citizenship, was arrested shortly after the killing, following an exchange of fire with the police in which he and an officer were wounded. The killer left a message in Arabic, which a photograph in a Dutch newspaper showed stuck to the victim’s chest with a knife.
On Tuesday, the police said the main suspect had no previous police record. But around midnight, the justice minister, Jan Hein Donner, and the interior minister, Johan Remkes, announced that the suspect was in fact known to the intelligence service. “He moved on the periphery of a group of Muslim militants, but he was not part of the hard core of the group,” Remkes said.
In a joint letter to Parliament on Wednesday, the ministers said that although the main suspect’s name had appeared to have been linked to others under investigation, there was no sign that he had been preparing acts of violence.
They said investigations were still going on as to “whether he operated on his own or had help from others in preparing and carrying out his act.” They added, “Given what is known now, there are serious considerations that the suspect acted from a radical Islamic conviction.”
The ministers said a message found on the body of the suspect and a second message were still being studied. In their letter, the ministers also said government officials and Islamic groups held extensive meetings on Tuesday to discuss how to fight extremism.
In June and July, the police, acting on information of the intelligence service, arrested five Islamic militants, one of them an 18-year old Moroccan, Samir Azzouz, who was found to have in his home maps and floor plans of key buildings in the Netherlands that were believed to be potential terrorist targets.
The buildings included floor plans of the country’s only nuclear power plant, Amsterdam Airport Schiphol, Parliament, the Defense Ministry and several other public buildings. Until the van Gogh killing, there had been no Islamist-linked violence on Dutch soil.
The spokesman for the intelligence service said that close to 40 persons had been arrested over the past several years on suspicions of planning acts of terrorism or recruiting others. Among the nearly one million Muslim immigrants or their descendants, there are few militants, according to a government report published in August. But it said that “small groups of young Muslims, mainly of North African origin, have appeared susceptible to radical views.”