Mario Pianesi is suspected of killing first wife by putting her on extreme form of ‘Ma-Pi’ diet

Italian police have opened a new investigation into Mario Pianesi, an influential businessman celebrated as a guru of macrobiotic food, over allegations he may have killed his first wife by putting her on an extreme form of his “Ma-Pi” diet.

Gabriella Monti died in 2001, two months after being diagnosed with acute hepatitis caused by aflatoxins, a fungal poison sometimes found in grain or nuts. Monti had had a stroke in 1997, after which she was cared for at home by her husband.

Pianesi had built up a following of thousands of customers who believed his cereals-based diet could cure serious illnesses. Police claim the diet may have exacerbated Monti’s already fragile state, leading to her death.

“Instead of curing her with traditional medicine, he tried to cure her at home with the diet,” Carlo Pinto, an investigator on the case, told the Guardian.

Pianesi, 74, is accused of keeping his wife’s illness hidden; he allegedly allowed few people to visit her. He is also suspected of trying to “eradicate proof” by exhuming her remains in 2013 and cremating them.

The new allegations emerged during an investigation into claims that Pianesi cultivated what police describe as a “macrobiotic sect” that manipulated people, denied them contact with the outside world and reduced them to slavery.

The investigation began in 2013 when a young woman whose weight had plummeted to 35kg (77lb) told police Pianesi had promised his diet would cure her illness.

Others came forward claiming Pianesi wielded power over those who had worked for his empire, a network of macrobiotic product hubs and restaurants, gradually leading them to lose control over their lives.

Pianesi and his second wife, Loredana Volpi, along with two representatives of UPM, were exposed in March and will go on trial over the sect allegations. His lawyers said in a statement that the latest allegations constituted “a description of facts that appear to be the fruit of rumours and conjectures”.

Pianesi started to make bold claims about his diet, modelled on the teachings of the Japanese philosopher George Ohsawa, in the early 1990s. Many people, particularly those diagnosed with HIV, attended his seminars in the hope of finding a cure.

It is alleged he tried to keep Monti’s death quiet because he feared people would believe his diet had failed; some of his followers had given up treatment for cancer in the hope of being cured by his food formula.

When news of the death came out, he allegedly told an audience of more than 100 people that it was their fault. “He accused us of killing her as he was unable to devote time to care for her because he was dealing with our problems,” said Gilbert Casaburi, a former chef within UPM.

The couple’s two sons defended their father in a local newspaper interview, saying they “lived under the same roof” and “ate the same food” as their mother. They also said their mother had not been “segregated” and that it was her choice not to have heart surgery after the stroke.