It was during a Polish trip, when Max Spiers from Canterbury was believed to be ready to expose a "major UFO cover-up" that he died.

That happened due to "natural causes" said Polish authorities. However, the mystery behind the "perfectly healthy 39-year-old" dying is a mystery that no one has been able to unravel. His family is sure that the reason was a "satanic cult."

The update on his death is that he "threw up two litres of black fluid" just before he died. Last Monday, during an inquest at Canterbury Coroner's Court, after his body had got repatriated, some new revelations indicated mysterious circumstances.

Just before he died, he had texted his mother. He told her to be sure to probe into the matter in case anything happened to him.

Coroner's investigations officer Caroline O'Donnell said: "When they returned, Mr Spiers became ill with a high temperature and was weak. The following day, Mr Spiers vomited two litres of black fluid. The friend called a doctor who attempted resuscitation before pronouncing him dead."

He was murdered, said his mother, Vanessa Bates. She said: "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. 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.

"Max was a very fit man who was in good health and yet he apparently just died suddenly on a sofa. 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."

Spiers' girlfriend, Sarah Adams, 31, revealed that he had become frightened of a Polish sect that he was linked to. He was convinced that they were posing a death threat to him.

She said: "We were used to getting death threats or stuff like that from people, but I think this time it seemed rather real. He'd been sent threats saying that him and me were going to die. He was going to expose black magic. He was going to expose some of the stuff he was working on involving political leaders and celebrities."

"He seemed anxious when we last spoke. He was terrified, he wanted to leave."