(WineSpectator) - For wine lovers and executives, the dinners were sorely tempting: dishes cooked by some of the world’s top chefs (Daniel Boulud, Tom Colicchio, Daniel Humm), paired with some of the rarest wines in the world (Domaine de la Romanée-Conti, Cheval-Blanc, Dom Pérignon) and featuring business-savvy speakers. Since 2013, the International Business & Wine Society (IB&WS) has offered members monthly dinners paired with lectures and chats with leading business minds.

Was it all an elaborate Ponzi scheme? The organization’s founder, Omar Khan, stands accused of taking money from investors and wine retailers to make the dinners happen and pocketing it instead.

Last week, 13 disgruntled clients filed a suit against Khan in New York state court, alleging fraud, misrepresentation, unjust enrichment and five other counts. They claim he owes them more than $8.3 million. Several other lawsuits are pending against Khan, the IB&WS and his other company, Sensei International, including one from a Burgundy hotelier and another from a wine retailer in Putnam County, New York.