A Swedish cartoonist who had multiple death threats against him for drawing the Islamic prophet Muhammad died in a car crash on Sunday.

In 2007, Lars Vilks became a target for jihadists when the newspaper Nerikes Allehanda published one of his drawings that depicted Muhammad as a dog. The subsequent threats against Vilks’ life, including a $150,000 bounty of assassination from the al-Qaeda-affiliated Islamic State of Iraq, became so severe that he would live the rest of his life under police protection, appearing in public on only a few occasions, often under the cover of intense security.

According to the BBC, Lars was reportedly travelling in an unmarked civilian police vehicle on Sunday when it “collided with a truck near the town of Markaryd in southern Sweden,” killing him along with the two police officers assigned to protect him in the head-on smash. He was 75.

Police chief Carina Persson confirmed the deaths and told a press conference: “There is nothing else for now that indicates that it was something else but a traffic accident”, Associated Press reports.

statement from police said it was still unclear how the collision occurred but once the vehicles hit one another, there was a large fire.

The truck driver, who has not been identified, has been taken to the hospital with serious injuries and will be questioned by police to determine any foul play.

“It is with dismay and great sadness that I received the news that our two colleagues and our security person died this afternoon,” said National Police Chief Anders Thornberg, as reported by the Daily Mail. “My thoughts go out to their relatives, families, friends and co-workers.

“I am also in contact with the police in the region to make sure that they get the support they need,” Thornberg added.

Anders Jakobsson, head of the special prosecutor’s office, said current evidence shows that the crash was an accident, not an intentional hit, though that may be subject to change as the investigation unfolds.

“With the information I have now, it indicates that it is an accident,” said Jakobsson. “But the investigation is at a very early stage.”

The Guardian profiled the multiple (oftentimes violent) attempts against Vilks life over the years prior to his fateful death on Sunday:

In September 2007, Vilks had a $100,000 bounty placed on his head by an al-Qaida faction in Iraq in response to his drawings.

In 2010, Swedish newspapers reprinted the controversial cartoon after two Muslim men were arrested and subsequently charged in the Republic of Ireland in connection with an alleged plot to murder Vilks.

In 2013, an American woman who called herself Jihad Jane was sentenced to 10 years in prison for plotting to kill him.

The Lars Vilks committee gave its freedom prize to Charlie Hebdo, the French satirical magazine, in October 2014 – three months before the terrorist attack on its Paris office.

In 2015, Vilks’s presence was a central feature of the Copenhagen terror attacks: he was the star speaker at a free speech event at a cafe where an Islamist gunman opened fire, killing a film director and wounding three police before going to a synagogue and killing a volunteer guard.

Stefan Sintéus, head of the regional investigation unit responsible for personal protection in the region, called Vilks’ death a tragedy, emphasizing the need to investigate the exact cause of death.

“This is an extremely tragic event. Now it is important for all of us that we do everything we can to find out what happened at the site and what caused the collision,” said Sintéus.