Traces of explosives have been found on some of the victims of an EgyptAir flightfrom Paris that crashed in the Mediterranean in May, according to Egypt’s civil aviation ministry.

A ministry statement issued on Thursday said a criminal investigation would now begin into the crash of flight MS804.

The plane was carrying 56 passengers and 10 crew when it crashed, including 40 Egyptians, 15 French citizens, two Iraqis, two Canadians and one passenger each from Algeria, Belgium, Britain, Chad, Portugal, Saudi Arabia and Sudan.

Analysis of the plane’s flight data recorder showed that there had been smoke in the toilets and avionics bay. Recovered wreckage from the jet’s front section showed signs of high temperature damage and soot.

Since the crash, small pieces of the wreckage and human remains have been recovered while the bulk of the plane and the bodies of victims are believed to be under the sea.

No one has claimed to have attacked the plane. The crash came seven months after a Russian airliner came down in the Sinai Peninsula shortly after taking off from an Egyptian Red Sea resort, killing all 224 people on board.

The local affiliate of Islamic State said at the time it had downed the Russian plane with an explosive device planted on board. Russia said the aircraft was likely downed by explosives.