Dutch artist Vincent Van Gogh did not commit suicide but was shot by a teenager obsessed with guns, claims forensic expert.

Dr Vincent Di Maio, an expert in gunshot wounds has stated that he believes the artist's injury was "not self-inflicted".

The theory was put forward in the 2011 book Van Gogh: The Life, when the two authors Steven Naifeh and Gregory White Smith, claim that the artist had been shot, perhaps accidentally by two boys. They believe that Van Gogh then decided to protect them by taking the blame himself.

But the murder theory was questioned by Louis van Tilborgh and Teio Meedendorp in a critical review in the Burlington Magazine, maintaining suicide as the cause of death.

As a result, the authors Naifeh and White Smith contacted forensic expert Dr Vincent Di Maio, who was a key witness in the George Zimmerman trial. In a Vanity Fair article, Di Maio said that it was highly likely that Van Gogh "did not shoot himself".

Di Maio also said that if Van Gogh did shoot himself there would have been "soot, powder tattooing and searing of the skin around the entrance".

He said: "These would have been grossly evident. None of this is described [in any of the forensic accounts]. This indicates the muzzle was more than a foot or two away (closer to two rather than one)."

In conclusion he said: "It is my opinion that, in all medical probability, the wound incurred by Van Gogh was not self-inflicted. In other words, he did not shoot himself."

A curator at the Van Gogh Museum also backed up Naifeh and Smith's claims, writing in an email. "I think it would be like Vincent to protect the boys and take the 'accident' as an unexpected way out of his burdened life."

According to the authors, the fatal shot was fired by a 16-year-old named Rene Secretan, who was with his brother at the fateful time . In the book Van Gogh: The Life, "Secretan liked to wear a cowboy costume brought from Paris, which he accessorised with a real gun, an erratic old .380 calibre pistol, for shooting squirrels, birds and fish."

Naifeh said, "So you have a couple of teenagers who have a malfunctioning gun, you have a boy who likes to play cowboy, you have three people probably all of whom had too much to drink."

The authors also discovered a "guilt-ridden" 1956 interview by Rene Secretan, who said he and his brother had known Van Gogh that summer and had tormented him mercilessly. Secretan was obssessed with America's Wild West and had borrowed a gun from the owner of the inn where Van Gogh was staying.

Secretan recalled in the interview that they goaded Van Gogh by playing practical jokes on him such as putting salt in his coffee and getting their girlfriends to tease him with fake seductions.

But the biggest flaw in the accidental homicide theory are Van Gogh's own words. According to Adeline Ravoux, the innkeeper's daughter who was 13 at the time of the accident in July 1890, two gendarmes questioned Van Gogh on his death bed. The artist said to them: "My body is mine and I am free to do what I want with it. Do not accuse anybody, it is I that wished to commit suicide."