Cleveland police previously confirmed to News 5 that they did not review Officer Timothy Loehmann's personnel file with Independence police before hiring him.
City officials announced Mr Loehmann's sacking and a 10-day suspension for his partner at the scene, Frank Garmback. The officers weren't charged criminally, but Tamir's mother settled a federal civil rights lawsuit with the city for $6 million.
Williams said Loehmann, who shot Rice, has been fired, not for the shooting but for inaccurate details on his job application.
The officer, Timothy Loehmann, had been on the force for less than a year before the November 2014 shooting.
"There's a 12 year old kid dead - people on both sides are going to say we didn't do enough or we did too much", Williams said Tuesday. The killing became part of a national outcry about police violence against minorities, particularly black boys and men. In 2015, a grand jury declined to bring charges against any of the officers involved. Loehmann shot Tamir. Garmback was driving their police cruiser.
The final decision to fire Loehmann was made after what Cleveland's Mayor Frank Jackson deemed an "exhaustive process" of investigation. Investigators say surveillance shows Tamir reaching toward his waistband and lifting up an outer garment.
Samaria Rice settled a federal civil rights lawsuit with the city past year for $6 million.
"This has been tough on our entire community", Cleveland police chief Calvin Williams said.
It's exhausting to read the many stories of police officers who not only go unpunished for their unjustifiable actions, but seemingly rewarded with "leave with pay".
Earlier this year, the 911 operator who took the call about Tamir was suspended for eight days for failing to tell the radio dispatcher that the caller had said Tamir could be a juvenile and the gun might be fake.