A $100 repair bill was the reason behind last week's mass shooting that killed seven people in California.
- 66-year-old Chunli Zhao is accused of murdering seven people and wounding another at two Bay Area mushroom farms where he had worked.
- Authorities say Zhao was enraged after his supervisor told him to pay $100 to repair a damaged forklift.
- Zhao has admitted to the killings and says he was bullied by coworkers at the farm.