The French accident investigation agency said Wednesday that it is not hopeful that the black box of the missing Air France airliner would be found. Paul-Louis Arslanian, head of the Office of Inquiries and Analysis (BEA), told a news conference that he is 'not optimistic' that the flight recorder will be recovered under the water. Intese investigations continue Wednesday after Air France Flight 447 crashed with 228 people on board into the Atlantic Ocean off the Brazilian coast Monday. Arslanian said due the complexity of the situation, they even had no exact idea of where the crash occurred and where the debris are, two days after the tragedy. He said there are no sign suggesting the plane had problems before takeoff from Rio de Janeiro on Sunday at 7 p.m. (2200 GMT). He warned that the investigation is likely to last for a long time and they didn't have enough information to determine whether the plane broke up in the air or upon impact with the sea. Earlier reports said the crash is likely caused by technical failure when it was hit by lightning and turbulence. The investigation agency said an initial report into the crash is expected to come out by the end of June, though the investigation 'will go as fast as possible.' Arslanian said it is unknown whether the chief pilot of the airliner was at the controls when tragedy occurred. Pilots on long-haul flights usually take turns at the controls to remain alert. Referring to the rescue efforts, the investigation agency said four teams have been sent out to conduct the inquiry of the case. The first team aims to locate the exact position of the crash; The second team is dedicated to dig out information relating to the cause of the crash and the flying history of the passenger jet; The third team is trying to find out the operation of the plane and the fourth focuses on the operation of the assistant equipments, it said. Also on Wednesday, French military spokesman Christophe Prazuck confirmed that the debris found at the sea belongs to the missing plane. 'The nature of the debris, the concentration of the debris ... all combines to prove that the debris from Air France 447 has been found,' he said. Until now, no signs of life have been found during the rescue efforts and both French and Brazilian officials said that it is likely that no life would survive. 