Just nine days before a shooter gunned down Baton Rouge police officer Montrell Jackson and two others in the line of duty, Jackson penned an emotional Facebook post calling for peace in the wake of Alton Sterling’s death.

Citing law enforcement and military sources, CBS News has identified the deceased gunman who killed three police officers and wounded three others in Baton Rouge on Sunday as 29-year-old Gavin Eugene Long, a former Marine who used the pseudonym “Cosmo Setepenra” online.

Authorities said that multiple officers were shot near a shopping center in Baton Rouge, Louisiana Sunday morning, according to the Associated Press.