A lot of criticism has surrounded the FBI’s database that is supposed to track all U.S. murders.
Now a USA Today investigation  has raised more serious questions about the accuracy of the database after discovering only a 57% accuracy rate for recording the killings of four or more people in a single event in the past decade.
Missing, for example, is the widely publicized Sandy Hook Elementary School shootings, which killed 26 teachers, students and administrators. Also missing is Aurora Colo., movie shootings.
The FBI responded that each of the states, which voluntarily submit the information, asked that the incidents be deleted.
According to criminologist James Alan Fox, about 90% of the homicides are included in the data.