Lars Vilks, an artist and freedom of expression activist whose cartoon depiction of the Prophet Muhammad on a dog’s body in 2007 made him the target of many assassination attempts, was killed in a car accident in Sweden on Sunday, police said.

Mr Vilks, who had been under police protection since 2010, was on his way to his home in southern Sweden when the civilian police vehicle he was traveling in swerved over the median and collided head-on with a truck, killing Vilks, 75, and his two bodyguards, police said.

The truck driver was taken to hospital with serious injuries.

“We are looking at the possibility that there was a tire explosion,” Stefan Sinteus, a regional police officer, said during a press conference on Monday. “There is no indication that this was a murder.”

Sinteus said the two police officers killed in the crash had been working with Vilks for several years.

The accident occurred on Sunday afternoon along a four-lane motorway in Markaryd, an area about 300 km southwest of Stockholm.

Many Muslims consider portrayals of Muhammad to be blasphemous, and cartoons such as that of Mr. Vilks have led to widespread backlash over the years. In 2005, a newspaper in Denmark published a caricature of Muhammad wearing a bomb-shaped turban that involved violent protests from Muslims.

In 2015, Islamic militants stormed the Paris office of the satirical cartoon Charlie Hebdo, which had reprinted cartoons, killing 12 people.

Whose black and white drawing was published by a regional newspaper in Sweden in 2007 and condemned by Muslims in the country, as well as by the Organization of the Islamic Conference, an umbrella organization of 57 Muslim majority countries.

Vilks then received death threats, and a group linked to Al Qaeda put a $ 100,000 premium on his head, forcing him to temporarily move to a secret location.

Mr Vilks was repeatedly threatened after the sign was published.

In 2010, he was assaulted while giving a lecture on freedom of expression at Uppsala University in Sweden. That year, two brothers were also arrested after trying to burn down his house. In a separate case, a suicide bomber sent messages to several Swedish news organizations that pointed out Vilks before he detonated two explosives in central Stockholm and killed himself.

In 2015, an armed man in Copenhagen attacked a café where Vilks spoke at an event called “Art, blasphemy and freedom of speech” and killed a filmmaker and injured three police officers. One of the organizers of the event, Helle Merete Brix, said she thought Vilks had been the intended target, even though he was unharmed during the shooting. Police later said they had shot and killed a man they believed was responsible for the attack on the café and another attack on a synagogue, in which one person was killed.

After the attacks, Vilks traveled with armed bodyguards, according to the Associated Press. “It’s like starting a new life,” he said. “Everything has changed. I have to understand that I can not go home. I probably have to find another place to live.”

Although he insulted Muslims and the threats to his life, Vilks said he did not regret the drawing. “I’m actually not interested in insulting the Prophet,” Vilks told The AP in 2010. “The point is, in fact, to show that you can. There is nothing so sacred that you can not violate it. ”