Previously undisclosed video of Michael Brown, recorded hours before the unarmed black 18-year-old was fatally shot by a white police officer in Ferguson, Missouri, has raised new questions about his final hours.

The footage shows Brown - whose death in 2014 prompted national protests and kindled a debate about how U.S. police treat minorities - at a convenience store the night before he was killed. It was unearthed by a documentary filmmaker, according to the New York Times.

Shortly after Brown's death, local police released video of a later visit to the same store, FergusonMarket and Liquor, which showed Brown pushing a worker before walking out with cigarillos in an apparent robbery.

Brown's family and protesters criticized the release of the video as an effort to demonize the teenager.

Witnesses have given conflicting accounts of his deadly encounter a short time later by police officer Darren Wilson. Local and federal investigations cleared Wilson of criminal wrongdoing.

The new video, which appears in the documentary "Stranger Fruit," an extract of which was published by the Times, shows Brown in an earlier, seemingly more amicable exchange.

The video shows Brown giving store employees what appears to be a small bag, the contents of which the employees pass around and sniff. One employee gives Brown two boxes of cigarillos in a carrier bag.

Brown takes a few steps away before turning back and handing the bag back to an employee who appears to stash it behind the counter.

Jason Pollock, the documentary filmmaker, said the video shows Brown exchanging marijuana for cigarillos and undermines the police account that Brown may have robbed the store.

"Mike traded the store a little bag of weed and got two boxes of cigarillos in return," Pollock says in the documentary. "He left his items at the store and he went back the next day to pick them up. Mike did not rob the store."

Brown's mother, Lesley McSpadden, also appears in the documentary, saying, "There was some type of exchange, for one thing, for another."

Jay Kanzler, a lawyer for the convenience store, was quoted by the Times as disputing the filmmaker's explanation, saying the store did not exchange anything with Brown.

"The reason he gave it back is he was walking out the door with unpaid merchandise and they wanted it back," Kanzler was quoted as saying.

Kanzler did not respond to a request for comment.