STOCKHOLM (AP) — The police car crash in Sweden that killed Swedish artist Lars Vilks last year was an accident, Swedish authorities said Wednesday, not a targeted attack on the cartoonist who lived under police protection since his controversial 2007 sketch of the Prophet Muhammad.

An exploding tire led the driver of the unmarked police car carrying Vilks to lose control over the vehicle, which crashed head-on with a truck on Oct. 4, Swedish authorities said in a statement. The crash killed three people, including the 75-year-old cartoonist.

Since Vilks was facing death threats for his drawings and had faced previous attempts on his life, the crash raised the question of whether the crash was a terror attack instead of an accident.

But the Swedish Prosecution Authority said it was “a tragic accident” as it announced the closure of the investigation into the Oct. 4 crash after an “extensive analysis, with a technical investigations on the spot and the questioning of witnesses.”

“In summary, it is most likely that a tire on the police vehicle exploded and then the driver lost control of the vehicle, which came over on the other side of the road and collided head-on with the truck,” Chief Prosecutor Per Nichols said. “The extensive investigation now shows that no crime has been committed.”

In parallel with the prosecutor’s investigation, police had conducted a preliminary investigation into possible murder in the case. That probe, which also was closed Wednesday, concluded it was an accident.

Vilks was largely unknown outside Sweden before his Muhammad drawing. At home, he was best known for building a sculpture of driftwood in a nature reserve in southern Sweden without permission, triggering a lengthy legal battle. He was fined, but the seaside sculpture — a jumble of wood nailed together in chaotic fashion — still draws tens of thousands of visitors a year.

The artist’s life changed radically after he drew a sketch of Muhammad with a dog’s body. Dogs are considered unclean by conservative Muslims, and Islamic law generally opposes any depiction of the prophet, even favorable, for fear it could lead to idolatry.

Al-Qaida put a bounty on Vilks’ head. In 2010, two men tried to burn down his house in southern Sweden and in 2014 a woman from Pennsylvania pleaded guilty in a plot to try to kill him.

The following year, a free-speech seminar that Vilks attended in Copenhagen, Denmark, was attacked by a lone gunman who killed a Danish film director and wounded three police officers.

Vilks, who was widely believed to have been the intended target of that 2015 attack, was whisked away unharmed by bodyguards. The gunman later killed a Jewish security guard outside a synagogue and wounded two more officers before he was killed in a firefight with police.

___

Jan M. Olsen in Copenhagen, Denmark, contributed to this report.

Copyright © The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.