The police made a serious mistake in granting a gun licence to Tristan van der Vlis, who shot dead six people in a shopping centre in Alphen aan den Rijn earlier this year, according to the official report into the incident.

The local Hollands Midden force knew Van der Vlis had spent time in a psychiatric institution but did not use the information when deciding whether or not to grant the permit in 2008.
The force is now to look again at all the gun permits which it has granted to make sure others have not slipped through the net. ‘This was a serious error and should never happen again,’ local police chief Jan Stikvoort told the news conference.
Arsenal
Van der Vlis went on his three-minute rampage in April this year, shooting dead six people and injuring 16 before turning a gun on himself. He also made four bomb warnings at different shopping centres in the commuter town, police chief Jaco van Hoorn told Monday’s news conference.
The investigation into the shooting spree has revealed that Van der Vlis was probably a paranoid schizophrenic who suffered repeated periods of depression. He also made at least two suicide attempts in 2008.
Van der Vlis had been a member of a gun club since 2007. The report shows the young man had built up his arsenal over several months, buying a gun and a revolver at the end of last year, a semi-automatic weapon and red dot sights in January and a bullet proof vest in March.
A check on his internet habits revealed a strong interest in other spree shootings, in particular the Columbine school killings. He was also interested in paranormal issues and had bought a special machine to help him hear ghosts.
Prior knowledge
Meanwhile, the public prosecution department is pressing ahead with a case against an acquaintance of the killer, whom it claims knew Van der Vlis was planning to go on the rampage.
Van der Vlis told him several times he was planning to shoot people, chief prosecutor Kitty Nooy told a news conference on Monday.
Nooy said the department had reached the decision to prosecute after very careful consideration. The man, who is not being held, faces a year in jail for failing to pass on the information to the relevant authorities.