On the Drifting Liferaft

A small sightseeing helicopter with one passenger was flying over the sea when it encountered a violent atmospheric disturbance and crashed into the sea before it could send out a distress signal. Fortunately, due to the buoyancy of the wings, the helicopter did not sink immediately, giving the pilot and passenger a chance to inflate the liferaft and move onto it.

The sea was calm. The liferaft was designed for four people, so it was more than sufficient for the two of them. There were five cans of emergency food on the raft, two of which were juice cans, to be used in place of drinking water.

"If we drift like this for two or three days, a search plane will probably come to rescue us. No need to worry," the pilot reassured the passenger.

However, half a month later, an international cargo ship discovered the liferaft, and both the pilot and the passenger were dead. The pilot had been stabbed to death with a knife, while the passenger had died of starvation, inexplicably clutching an inflated air tube with one finger of his left hand. On the raft, there was a bloody knife and four empty cans of food, with one can remaining untouched.

"These two must have fought each other with the knife over the last can of food, right?" "If that's the case, why didn't the surviving attacker eat the can of food and instead starve to death?" The crew of the cargo ship found it all very puzzling.

Can you deduce what happened on the drifting liferaft?