2. Prohibition deaths
It was back in the 1920s and the government decided that no more booze should be sold. With legal alcohol no longer an option people turned to bootleg liquor until people started dying. Those who were prone to listen to conspiracy theories believed that the government had had something to do with it.
It turns out, it did. It seems that the federal government put together a program in 1926 in an effort to show the people that alcohol was indeed deadly. Seized bottles were spiked with poison and put on the market, leading to many deaths among the drinkers.