Director Michael Moore found making his new documentary SICKO one of the hardest movies to make - because some of the castmembers died before filming on the project wrapped. Sicko chronicles the struggles of everyday Americans as they attempt to get adequate healthcare, and Moore sparked controversy in the film by accompanying a group of sick 9/11 rescue workers to Cuba, where they were hoping to receive free treatments for their ailments. But the 53-year-old was undeterred by the tragic deaths, and tried to lighten the mood of the documentary by using humour. He tells U.S. talkshow host Larry King, "It was (a hard movie to make). It was because we dealt with a lot of people who were sick and dying. Some died while we were making the film. So that's why I thought it was very important that there be a - a certain amount of comedy and humour in the film to relieve the... disparage." Moore himself is currently under investigation by U.S. government officials, who claim he broke federal trade laws to make parts of the hard-hitting new film in Cuba.