The death of a reveller at the Burning Man festival in Nevada is being treated as suspicious, police have said.

Shane Billingham, 33, was found unconscious in his car at the vast desert party on Thursday evening.

The New Zealand national had “poisonous” levels of carbon monoxide in his blood, a post mortem has now discovered.

An unidentified “controlled substance” was also found to be an exacerbating factor, the Washoe County medical examiner’s office said in a statement.

Following the report, Pershing County Sherriff’s Office said it is investigating the death as suspicious.

The Best Of The Artwork At Burning Man 2018 Show all 12 1 /12 The Best Of The Artwork At Burning Man 2018 The Best Of The Artwork At Burning Man 2018 BEBOT was described as a 'cute and friendly' robot - a comic book robot created on a huge scale. But there's a message behind it - the cute aesthetic found in digital culture can lower our barriers to privacy and clouds our perception to risk, according to the creators, and this was their attempt to highlight that. The Best Of The Artwork At Burning Man 2018 This satirical installation showed an office space and a living room surrounded by barbed wire, security cameras, and people in orange jumpsuits. A TV commercial boasting of this secure way of living played on loop in the centre. The Best Of The Artwork At Burning Man 2018 Artist Olivia Steele's old-school cinema-style sign was updated with new messages each day, perfectly timed to coincide with the sunrise. It featured everything from the glib - "WTF" and "S*** just got real" - to the thoughtful - "I forgive you, now it's your turn." The Best Of The Artwork At Burning Man 2018 In keeping with this year's "I, Robot" theme, this seemingly half-submerged robot appeared on the playa, with eyes closed in apparent contemplation. The Best Of The Artwork At Burning Man 2018 This cute country cottage looked almost mystical thanks to the gnarly wooden structure which surrounded it. The Best Of The Artwork At Burning Man 2018 'Inside, Outside, Around and Through' is a series of locked doors. The solution? Go around them. The message is simple: in everyday life we may be restricted by ideas of what we feel we cannot do, when the solution to overcoming our problem is right there. The Best Of The Artwork At Burning Man 2018 These simple trees appeared on deep playa, a small wooden forest on a barren landscape. The Best Of The Artwork At Burning Man 2018 "Odd Jelly Out" draws inspiration from Jelly Babies, and the figures were crafted from steel and fibreglass. According to the artist, their remote position on the site is meant to evoke the loneliness of those on the fringes of society. The Best Of The Artwork At Burning Man 2018 The star piece of this year's Burning Man was arguably this huge, mirrored ball, which became a gathering post and a waypoint for people at the festival. The Best Of The Artwork At Burning Man 2018 The 100-foot-long rainbow sat close to the centre of the site, with steps up the sides to allow passers-by to get a great view of the whole site. The Best Of The Artwork At Burning Man 2018 Out of place? Yes, but that's the point. This giant polar bear stood in the middle of the desert. Take a look at the expression, though: the creators say it's looking for allies in the fight against climate change. The Best Of The Artwork At Burning Man 2018 This embracing metal couple dazzled - literally. Its intricately curved surface meant the beating sun bounced off in every direction.

Burning Man is widely regarded as one of the world’s weirdest and wildest counter-culture festivals, attracting some 80,000 people from across the planet. Among the entertainments on offer during this year’s week-long event – which runs to Monday – are orgies and beer bong breakfasts.

Witnesses said Mr Billingham was given CPR by bystanders after being discovered in his vehicle at about 6.30pm local time.

He was taken to a medical tent but was later pronounced dead.

Support free-thinking journalism and attend Independent events

A makeshift memorial for the professional craftsman has since been set up in the Beats Boutique camp where he was staying. A wooden medallion, jacket and boxes of essential oils are among items left there.