A Broward County jury found Scot Peterson not guilty on all counts in what prosecutors said was his failure to confront the gunman who murdered 17 people at a Parkland, Florida, high school more than four years ago in what remains the deadliest high school shooting in U.S. history.

After 21 hours of deliberations over four days, the jury of three men and three women decided unanimously that Peterson will not be criminally convicted of the charges against him.