Lesley McSpadden, right, the mother of 18-year-old Michael Brown, watches as Brown's father, Michael Brown Sr., holds up a family picture of himself, his son, top left in photo, and a young child during a news conference Monday, Aug. 11, 2014, in Ferguson, Mo. Michael Brown, 18, was shot and killed in a confrontation with police in the St. Louis suburb of Ferguson, Mo, on Saturday, Aug. 9, 2014. (AP Photo/Jeff Roberson)

FBI issues warning to law enforcement

The FBI sent warnings to law enforcement across the country, alerting them to any potential reaction to a Missouri grand jury verdict.