From Article:
"Instead of knocking on Arias’ window to further investigate the situation, Light admits the officer swung the passenger side door open without informing the driver. After noticing the disassembled gun, Gilette fired four shots, striking Arias once in the head."
Did he see the gun before or after he forced himself into the victim's car?
This is starting to seem like a No-Knock Conditioning taking effect...