French police step up search for bodies of Chinese tycoon and two others who died after helicopter crash as they surveyed vineyards he had just bought Lam Kok, 46, was surveying the property from above with three others when the aircraft plummeted into the Dordogne river Mr Kok's 12-year-old son, winemaker James Gregoire, interpreter Peng Wang and Shun Yu Kok, Mr Kok's son, were also on board Police were scouring the river last night for signs of them, and began their search again today, which has involved more than 100 officers Divers found the body of Shun Yu Kok underwater in the wreckage French police have stepped up their search for a Chinese billionaire and two others feared dead after their helicopter crashed. Lam Kok, a 46-year-old Chinese businessman, was surveying a newly-purchased vineyard in southwest France with his interpreter and advisor Peng Wang and or winemaker James Gregoire when their aircraft crashed into the Dordogne river. Officer last night recovered the body of Lam's 12-year-old son, Shun Yu Kok, from the back of the wrecked helicopter, which was lying in 23ft of water in the Dordogne river. Rescue: French police scour the Dordogne river in search of Lam Kok and his fellow passengers Efforts: More than 100 police are involved in the search after the helicopter crash on Friday Desperation: A relative of Mr Kok's shouts his name from the riverbank The four had boarded the helicopter, piloted by Mr Gregoire, on Friday to make a celebratory tour of a Bordeaux chateau and wine-growing estate that Lam had just bought from him. After pausing the search on Saturday night, divers resumed scouring the cold waters of the Dordogne around 9.00am today. 'We are meticulously combing the area, with practically no visibility, almost by hand,' local gendarmerie commander Ghislain Rety said. Police said strong currents were hampering the search. Hunt: Police sources said that the search was difficult because of very poor visibility Helicopters with infra-red cameras were flying over the river and a special sonar designed for finding bodies had arrived from the French city of Strasbourg, Mr Rety said. Some 100 police were searching along the riverbanks and reinforcements were expected. Officials were expected to carry out an autopsy on Mr Kok's son today, but officials said there was little hope the reasons for the crash would be identified quickly. 'The causes of the accident have not been determined at this stage and most likely will not be for several weeks,' local prosecutor Christopher Auger said. Missing: Chinese tea tycoon Lam Kok stands with James Gregoire and their respective wives after sealing the deal on his purchase of the Chateau de la Riviere in Bordeaux, France, just an hour before going missing Rescue operation: Search lights shine across the Dordogne after the helicopter Mr Kok and Mr Gregoire were travelling in apparently plunged into the river as they made an aerial survey of the property Mr Kok's wife pulled out at the last minute saying she was 'scared of helicopters', an AFP photographer at the scene said. Mr Gregoire had bought the land and its 8th Century chateau in 2003 after Jean Leprince, the previous owner, died when his aircraft also crashed nearby. All in the helicopter had been taking part in a celebratory press day, marking the sale of the historic estate.