Complex sentence: A death squad composed of thirty three Rio Military Police was responsible for carrying out this act of violence, supposedly done out of revenge for the killing of four police officers two days prior, who were allegedly involved in the extortion of drug traffickers.
Split into simpler sentences: A death squad composed of Rio Military Police was responsible for carrying out this act of violence. They supposedly did so out of revenge for the killing of four police officers two days prior, who were allegedly involved in the extortion of drug traffickers.