By Marice Richter

DALLAS (Reuters) - Texas police on Sunday were trying to figure out what prompted a young black man to drive his car into a car dealership, and why a white police officer still in training fatally shot the unarmed 19-year-old four times.

Christian Taylor became the latest unarmed black man to die at the hands of a white police officer after officials said he was seen on security surveillance tape vandalizing cars at an auto dealership inArlington.

Taylor was shot four times by Arlington police Officer Brad Miller, 49, who was still undergoing training with the department, Arlington police Chief Will Johnson said on Saturday. The Tarrant County Medical Examiner's Office found Taylor had gunshot wounds to the neck, chest and abdomen.

But Johnson did not explain what led to what he described as a confrontation inside the car dealership building that led Miller to open fire on Taylor, while a second police officer used a Taser. The officers were not wearing body cameras.

Brad1 Officer Brad Miller, who is accused of fatally shooting an unarmed black man, is seen in a handout photo provided by the Arlington (Texas) Police Department on Aug. 7, 2015. The FBI has been asked to help investigate the death of Christian Taylor, who was suspected of driving a vehicle through the window of a car dealership, Arlington's police chief said Saturday. Photo: Reuters/Arlington Police Department

Taylor's brother Joshua, 23, said the family wanted details of what happened, calling the information from the police "blurry."

"Until we get concrete facts, we won't know what happened," Joshua Taylor told Reuters in a phone interview.

"He was a really good guy. He was family-oriented. He was an A student and had he everything going for him," Taylor said, adding that his brother had "recently given his life to God."

"He was happy, everything was great. He was trying to touch people's lives," Joshua Taylor said.

His father Adrian Taylor said he had no idea what led Christian, a college football player at Angelo State University, to smash a car though the window of the dealership on Friday.

"You know, it could have been too much drinking. He could have been wrong place at the wrong time,"Adrian Taylor told the CBS Dallas TV affiliate, CBS 11.

Taylor's death came just ahead of the one-year anniversary of the fatal shooting of Michael Brown, 18, at the hands of a white officer in Ferguson, Missouri, that ignited protests across U.S. cities.

On a Twitter account appearing to belong to Christian Taylor, the man commented about police violence. "Police taking black lives as easy as flippin a coin, with no consequences smh," says one message posted in December, using the acronym for shaking my head.

More recently, the Twitter feed had posts about God and personal change. "Never believe in fear again. Yall have seen my change... I'm a whole new person," one post says.

Miller was placed on leave after the shooting and Johnson said he had asked the Federal Bureau of Investigation to help investigate Taylor's death. The FBI could not be reached for comment on Sunday.

The two police officers were responding to a call from a security company on Friday about a burglary at the dealership in Arlington.

Edited portions of security surveillance video released to the media shows Taylor jumping on top of cars parked outside dealership and attempting to stomp out a front windshield. It does not show the shooting or the moments leading up to it.

Johnson said when the officers arrived they found Taylor had driven a vehicle into the front of the building. He ran to another part of the building, where he tried to escape through a locked door.

The Fort Worth Star-Telegram reported that Taylor was sentenced to six months deferred-adjudication probation in December for unauthorized possession of prescription painkillers.

Joshua Taylor described the incident as "normal teenage stuff" and said Christian had "turned his life around."

(Reporting by Marice Richter in Dallas and Laila Kearney in New York; Editing by Jill Serjeant and Lisa Shumaker)