A now-former San Antonio police officer was charged on Tuesday with two counts of aggravated assault in last week’s shooting of a teenager who was eating a hamburger in his car in a McDonald’s parking lot.

James Brennand, 25, was charged in the October 2 shooting of Erik Cantu, 17, according to a police statement.

Mr Cantu’s family said in a statement on Tuesday that “there is no improvement in his condition. He is still unconscious and is on life support”.

“The last two days have been difficult, and we expect more difficulty ahead, but we remain hopeful,” the statement continued.

Their attorney, Brian Powers, said it is “an incredibly difficult time for them”.

A rookie officer, Brennand reported the vehicle in which Mr Cantu sat had evaded him the night before during an attempted traffic stop.

Brennand said he suspected the vehicle had been stolen.

In body camera footage released by police, Brennand opens the car door and tells Mr Cantu to get out.

The car drives backward, door open, and the officer fires multiple times into the vehicle. He continues to shoot as the car drives away.

Investigators quickly determined that the use of deadly force was unwarranted, Brennand was swiftly fired, and charges against Mr Cantu of aggravated assault and evading arrest were dropped.

In an appearance on CNN on Tuesday morning, police chief William McManus had said he expected Brennand to be charged with aggravated assault for the shooting and murder in the event Mr Cantu dies.

Mr McManus said Brennand’s body camera video of the October 2 shooting was “horrific”.

“There is no question in anybody’s mind looking at that video that the shooting is not justified,” Mr McManus said.

Police officials and the Bexar County District Attorney’s Office did not immediately return messages from The Associated Press. Brennand has no published telephone number and could not be reached for comment.

Mr Cantu’s condition, as related in his family’s statement, is in stark contrast to that provided by police officials in the wake of the shooting that Mr Cantu was hospitalised in stable condition.

“We’d like to correct any misrepresentations that Erik is in ‘stable condition’ or he is ‘going to be fine.’ That is not true. Every breath is a struggle for Erik. We ask for everyone’s continued prayers for our son,” according to the family statement.