A black 18-year-old killed by police in St Louis earlier this week was shot in the back, authorities said on Friday, adding weight to protests that have challenged the official account of his death.



A preliminary autopsy by the city medical examiner determined that Mansur Ball-Bey “sustained a single fatal gunshot wound to his back”, according to a statement released by the St Louis metropolitan police department.

Police chief Sam Dotson acknowledged to the St Louis Post-Dispatch, which first reported the autopsy finding earlier on Friday, that it may mean Ball-Bey was shot while running away. He said, however, “I just don’t know yet.” The shooting is being investigated by the department itself.

Renewed protests broke out in St Louis on Wednesday evening after Ball-Bey was killed as officers executed a search warrant at his aunt’s home that morning. Police deployed teargas and smoke canisters to sweep demonstrators from the streets and nine people were arrested, as some threw rocks and bottles at police lines.

Mansur Ball-Bey, 18. Photograph: Instagram

Police swiftly said Ball-Bey “turned and pointed a gun” at officers after fleeing the home raid through the back door with another teenager. “Fearing for their safety, two officers fired their weapons,” they said on Wednesday. Some witnesses have insisted, however, that the 18-year-old was not carrying a weapon and was shot as he ran away.

Two white male police officers shot at Ball-Bey, police said. The pair, 33 and 29, have both worked at the department for seven years. Their names have not been released and it is not clear which officer’s shot struck Ball-Bey. The officers have been placed on leave.

At a press conference on Friday afternoon, Dotson insisted the medical examiner’s findings “do not change the scope of the investigation” and pledged the inquiry would provide a “complete picture” of what happened.

Dotson said police had spoken to a witness who supported the officers’ allegations against Ball-Bey. He said the witness had, however, also reported the 18-year-old “tossed” the gun at some point, but did not elaborate further.

Dotson said that in preparation for possible further unrest, St Louis city officers were working 12-hour shifts. He appealed for calm from protesters and urged a 14-year-old boy he said escaped after Ball-Bey’s shooting to come forward.

“We will continue to share as much information as we can as quickly as we can,” said Dotson.

The shooting took place about nine miles south-west from where Michael Brown, an unarmed black 18-year-old, was shot dead in August last year by a white police officer in the St Louis suburb of Ferguson. Ball-Bey’s death also fell on the anniversary of the fatal police shooting of Kajieme Powell, a black 25-year-old who had a knife, nine miles to the east.

Brown’s shooting unleashed months of protests in the region and elsewhere, thrusting issues of race and criminal justice on to the national political stage.

Police alleged Ball-Bey was carrying a stolen gun equipped with an extended magazine of ammunition. They said four guns and some crack cocaine were recovered from the scene.

Friday’s statement said the metropolitan police department’s “force investigative unit” would complete a full inquiry into the shooting. Its report will be given to local and federal prosecutors – Jennifer Joyce, the St Louis circuit attorney, and Richard Callahan, the US attorney for the eastern district of Missouri – for review, the statement said.