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The Arlington, Texas, police recruit who fatally shot an unarmed college football player during a break-in at a car dealership early Friday has been fired for "exercising poor judgment," the police chief said Tuesday.

Christian Taylor, 19, was fatally shot by Arlington Police Officer Brad Miller, 49, after police were called to a break-in report at the Classic Buick GMC dealership at around 1:06 a.m., police said.

Miller, a recruit officer who was undergoing supervised field training, entered the building alone and without telling other officers, setting into motion a chain of events that led to the deadly shooting, Arlington Police Chief Will Johnson told reporters Tuesday.

Arlington Texas Police Officer Brad Miller. ARLINGTON POLICE DEPARTMENT via EPA

Miller told investigators he feared for his safety and thought he would be overpowered, and that he believed he was alone even though his training officer was four feet away, Johnson said.

"This fear and feeling of isolation was the result of his poor decision to enter the building without assistance and without an arrest plan," Johnson said.

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Police were called to the dealership after Taylor allegedly kicked in the windshield of a car and then crashed his Jeep into a showroom door, police said.

Police found Taylor roaming inside the dealership, and an officer spoke with him through a glass door and ordered Taylor to get on the ground, Johnson said. Taylor refused, and held up a set of keys and told the officer he was there to steal a car, Johnson said.

Miller and his supervising officer, Cpl. Dale Wiggins, were tasked with setting up a perimeter. After Wiggins stopped to talk with the officer who made contact with Taylor, Miller saw the crashed car and entered the dealership on his own and without telling other officers, Johnson said.

That decision put the other officers at risk, Johnson said, and Wiggins had to rush to rejoin Miller. By the time he arrived Taylor was allegedly cursing and moving towards Miller in a threatening manner, Johnson said.

Wiggins heard a "pop" and thought Miller fired his Taser stun gun, but Miller had actually fired his service weapon, Johnson said. The supervising officer drew his own Taser and used it, and Miller fired three more times, Johnson said. It is believed Taylor was 7 to 10 feet away from Miller when the officer fired, he said.

Taylor, a sophomore at Angelo State University in San Angelo, never made any physical contact with any officer, Johnson said. A bulge in Taylor's shorts pocket officers believed could have been a weapon turned out to be a wallet and a cell phone, he said.

"This is an extraordinarily difficult case," Johnson said. "Decisions were made that have catastrophic outcomes."

The investigation is continuing and will be forwarded to the district attorney's office for consideration and for submission to a grand jury, Johnson said. The criminal investigation is expected to take several weeks. The supervising officer will not be disciplined in the case, Johnson said.

The Arlington Municipal Patrolman’s Association said in a statement Tuesday that "every officer, every employee, every American has a right to be free from a rush to judgment without the facts."

"The Arlington Municipal Patrolman’s Association supports Officer Miller’s right to be judged fairly and completely on facts instead of a snapshot developed in only days," the statement said. "Investigations take time and as Chief Johnson acknowledged, this investigation is not close to being concluded.

"With that said, our thoughts and prayers are with the Taylor family in this time of grief. We again ask that citizens obey the commands of police officers in order to prevent these tragedies from occurring in the future."