Boston Police Officer John O'Keefe, his girlfriend Karen Read and a group of other friends, including fellow officers, went out drinking at C.F. McCarthy's bar in Canton, Massachusetts at around 9 p.m. A major snowstorm had begun.

Karen Read’s second murder trial was a rematch for the lawyers after the first ended in a hung jury last year. CNN correspondent Jean Casarez answers key questions about the case after Read was acquitted of murder Wednesday.