Why did Maricopa County have to be sued for this to be released?

WARNING GRAPHIC.... #ARIZONA, #MARICOPA CO, OFFICER SHOOTS ISIS TERRORIST AFTER CHARGES WITH A KNIFE

How many heard about this? County had to be sued to release the info.

Ismail Ahmed stated he wanted to do something in protest on behalf of the people in Palestine & Middle East pic.twitter.com/fHy2x3qapn

— Cindyseestruth (@cs00582sc) February 17, 2019