As a leading conspiracy theorist, the investigations of Max Spiers took him to some "dark places".

And now his mysterious death aged just 39 has left his family fearing he was murdered.

Found dead on a sofa in Poland, ex-Canterbury schoolboy Mr Spiers was ruled to have died from natural causes, despite no post-mortem examination being carried out on his body.

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But in a chilling text message to his mum just days before his death, he wrote: “Your boy’s in trouble. If anything happens to me, investigate.”

English teacher Vanessa Bates, 63, says her son had spent many years investigating UFOs and looking to expose government and other cover-ups.

VIDEO: Vanessa talks about why she wants an investigation into his death.

She fears his work around the world may have made him enemies who wanted him dead.

“He was making a name for himself in the world of conspiracy theorists and had been invited to speak at a conference in Poland in July,” she said.

"Your boy's in trouble. If anything happens to me, investigate" - Max Spiers, to his mum

“He was staying with a woman who he had not known for long and she told me how she found him dead on the sofa.

“But I think Max had been digging in some dark places and I fear that somebody wanted him dead.”

Mr Spiers grew up in Canterbury and was a former St Edmund’s School pupil and classmates with Hollywood actor Orlando Bloom.

After a few years living in America, he returned to the city and was staying with his mother in Merchants Way.

He made a career out of investigating UFO sightings and alleged cover-ups.

More recently, he was said to be probing into the lives of well-known figures in politics, business and entertainment.

His unexplained death, and its subsequent treatment by the authorities, has left many online followers convinced he was killed by government agents.

Conspiracy theorists have long been convinced that UFO chasers who get too close to the truth are “bumped off” by the secret services or so-called men in black.

On one website, Project Camelot, a blogger wrote: “The entire circumstances are suspicious and I urge everyone to encourage the release of details about what really happened and call for an autopsy.”

Another, Craig Hewlett, added: “If it wasn’t true what he talks about then why would they kill him? Healthy people don’t just get sick and die, they get poisoned.”

Mrs Bates buys into the theories.

“Max was a very fit man who was in good health and yet he apparently just died suddenly on a sofa,” she said.

"We all want answers to this and I will continue to fight to get to the truth" - Vanessa Bates

“All I have is a death certificate from the Polish authorities that it was from natural causes, but no post-mortem was done so how can they tell that?

“They are also refusing to release any paperwork about it to me because, absurdly, I don’t have his written permission.”

Mr Spiers is buried in Canterbury cemetery after his mother arranged to have his body flown home a week after his death.

A post-mortem examination was carried out by a pathologist in east Kent, but Mrs Bates says that more than two months later she still does not know the result, or whether there will be an inquest.

She said: “Apparently, he had not suffered any obvious physical injuries but he could have been slowly poisoned, which is why the results of toxicology tests from his post-mortem are so important.

“He has a brother, Josh, and sister, Becky, who are both devastated, as are his two boys. We all want answers to this and I will continue to fight to get to the truth.”

The North East Kent coroner’s office would only confirm the death was at the “very early” stages of investigation.