The murder of a Dutch lawyer representing a witness in a high-profile organised crime trial has sent shockwaves through the Dutch legal community and has led to additional security measures for judges, prosecutors and others involved in the trial.

Derk Wiersum, 44, was shot dead in broad daylight near his home in Amsterdam on Sept. 18. He was representing a witness known as Nabil B in a case against a group of men charged with drug-related killings. Nabil B is a key witness for the prosecution in the case against 16 men accused of five murders and one attempted murder in the Netherlands between 2015 and 2017.

One of Wiersum's two children was at home at the time of the killing.

The Council of Bars and Law Societies of Europe said in a statement they were "utterly shocked by the murder."

The CCBE said the murder of lawyers exercising their professional duties was an "unacceptable attack on the legal profession", whose role was "essential to guarantee access to justice and protection of human rights and fundamental freedoms for all citizens—particularly through the protection of the rights of the defence and the guarantees of a fair trial."

"Attacks against lawyers are attacks against the rule of law," the group said, adding that the CCBE would continue to fight so lawyers could perform their professional duties "without fear of reprisal, hindrance, intimidation or harassment, in order to preserve the independence and integrity of the administration of justice and the rule of law."

Dutch media is reporting that extra security measures have been taken for dozens of people, including judges and prosecutors involved in the Taghi trial. Some of them will receive round-the-clock personal protection, the Dutch television channel NOS reported.

According to a report Tuesday in the Dutch newspaper NRC Handelsblad, security around the court in Schiphol East, where the case is being heard, has been stepped up with the addition of officers from the Special Interventions Service. The heavily armed officers wear all-black uniforms with bulletproof vests, balaclavas and special helmets.

Mark Rutte, the Dutch prime minister, called the killing "incredibly disturbing," and Ferd Grapperhaus, the Dutch justice and security minister, said the murder was an "an attack on our constitutional state," adding: "Organised crime has crossed a line."