The girlfriend of a world famous conspiracy theorist feared murdered by "enemies" will be quizzed by police, it has been reported.

Max Spiers, from Canterbury, was found dead by a friend in Poland just days after texting his mother: "Your boy's in trouble. If anything happens, investigate."

Vanessa Bates fears her son – who made a name for himself in the shadowy world of conspiracy theorists and sought to expose government cover-ups – may have been murdered because his work “made him enemies”.

Mr Spiers, 39, was found dead on his girlfriend's, Monika Duval, sofa in July 2016 - days before he was due to speak at a conspiracy theory conference in Poland.

He vomited two litres of black fluid before his death, an inquest heard in December.

It is reported that police have now opened an investigation into involuntary manslaughter and are looking to question science fiction writer Duval, who was with him at the time of his death.

Lukasz Lapczynski, prosecutor in Warsaw, told the BBC: "Our initial investigation indicates that it was Mr Spiers's partner [who called the ambulance], but the nature of this relationship is unclear."

He added: "The nature of this relationship will be determined during the investigation.

"The doctor started resuscitation which was not successful. As a result of the doctor's decision, the police weren't involved in conducting additional procedures.

"The information about Max Spiers's death reached the prosecution office on August 30 when the body had already been transported to the UK. We couldn't do a post-mortem which is essential in such cases.

"The prosecutor told me he plans to interview everyone that was present when Max died. We know Monika was there, but it's unclear who else was around."

Father-of-two Mr Spiers, who lived in Merchants Way, Canterbury, died in Jozefow, Otwock, on July 16.

His death was initially dismissed as from natural causes by the Polish authorities.

His body was repatriated to the UK but a post mortem examination at Margate’s QEQM Hospital was unable to determine how he had died.

Mrs Bates, 63, said: “I think Max had been digging in some dark places and somebody wanted him dead.”