“Your boy’s in trouble. If anything happens to me, investigate.”

That was a text message that conspiracy theorist and UFO expert Max Spiers sent to his mother days before he was discovered dead in Poland. Spiers, who was in Poland to give a talk about conspiracy theories and UFOs, was found dead on a sofa in a Warsaw apartment.

Medical examiners declared that Spiers died from natural causes, and several friends claim that Spiers “vomited a black liquid before his death.”

“A person has died here, and I don’t think it’s good enough [that] somebody who just took normal medication should end up vomiting, spewing black liquid, whatever it was,” Spiers’ friend Miles Johnson told conspiracy website Project Camelot. According to Spiers’ mother, Vanessa Bates, the Canterbury, England, native had been invited to Poland back in July to speak at a conference. She said that he had been staying in an apartment with a woman he barely knew, who informed Bates of his death.

“I think Max had been digging in some dark places, and I fear that somebody wanted him dead,” Bates told the New York Post, later adding, “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 postmortem 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.”

It has been more than two months since a pathologist conducted a postmortem on Spiers’ body, though Bates has yet to be informed of any result.

“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 postmortem are so important,” Bates said.

Spiers left behind two children. He was 39 years old.