WASHINGTON - New surveillance footage has emerged of the black teenager Michael Brown suggesting he had not in fact robbed a Ferguson, Missouri convenience store hours before he was shot by a white police officer. Brown's 2014 death sparked weeks of sometimes-violent protests, and ignited a national debate about race relations and law enforcement in the United States.

The new video, used in documentary "Stranger Fruit" that premiered Saturday at the South by Southwest film festival, suggests Brown's altercation with store employees in a separate visit to the shop was tied to a suspected drug transaction with the shop employees. In the video, dated around 1:15 am on August 9, 2014, Brown can be seen handing over the counter a small bag, which store employees then pass around and smell before a store clerk gives Brown two large boxes of cigarillos.

Just before leaving the store, Brown returns to the counter and has the clerk hold the bag with the cigarillos behind the counter.

Ten and a half hours later, when Brown returns to the store, video surveillance footage previously released by police shows him standing behind the counter with his arms behind his back. He then reaches over the counter and grabs boxes of cigarillos. On his way out of the store, he shoves a clerk out of his way.

"Stranger Fruit" director Jason Pollock, who obtained the new footage, says it contradicts Ferguson police's version of the events.  In the film, he says Brown gave a small bag of marijuana to store employees and received cigarillos in exchange, and that he had left the cigarillos behind the counter for safekeeping.

"There was an understanding, and that's what you are going to see in that video," Brown's mother Lesley McSpadden says in the documentary. "There was some type of exchange for one thing, for another."

Pollock concluded: "Mike did not rob the store." A lawyer representing the convenience store and its employees disputed that account. "There was no transaction," Jay Kanzler told The New York Times.

"There was no understanding. No agreement. Those folks didn't sell him cigarillos for pot. The reason he gave it back is he was walking out the door with unpaid merchandise and they wanted it back."

The new video does not shed light on the subsequent and ultimately fatal altercation between Brown and police officer Darren Wilson. Ferguson reached a deal with the US Justice Department after the shooting to reform its police department and courts. Federal investigators had found a widespread pattern of racial discrimination and multiple violations of citizens' constitutional rights in the St. Louis, Missouri suburb.

Brown's killing was among a series of deaths which exposed entrenched problems with US police tactics and black men. The events sparked mass protests and helped launch the Black Lives Matter activist movement against law enforcement violence seen as racist.