Peterson retired after being massacred in February 2018 in Parkland, Florida, in high school where 17 people died. He was released Tuesday at a hearing of new sheriff Gregory Tony.
The dismissal could affect Peterson's retirement benefits, Tony said.
Peterson, a resource resource officer, is charged with negligence, culpable negligence, and perjury in connection with the deadly shootout.
Days after the massacre of 14 February. It was seen as Peterson took position in front of the Marjory Stoneman Douglas High School building in front of the 1200s building, instead of entering the building where an armed man shot at students and staff.