A mobile phone video that shows a witness raising his hands in the air immediately after the fatal shooting of a black 18-year-old by a white police officer in the US state of Missouri appears to support previous accounts and could bolster arguments that he was surrendering when shot, legal experts say.
The video, first aired by CNN, shows two landscapers who were working near the street where Michael Brown, who was unarmed, was shot by officer Darren Wilson on August 9.
In the video, a man can be heard saying, "He had his (expletive) hands up," while one of the workers raises his own hands in the air.
Brown's shooting spurred several days of sometimes violent protests in Ferguson, a predominantly black St Louis suburb, and a nationwide debate about the relationship between young black men and law enforcement.
The man who took the mobile phone video, who spoke on condition of anonymity because he feared for his safety, said the voice was that of the worker raising his hands, but that isn't clear on the video.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
The workers are not from Ferguson, the St Louis suburb where Brown was shot, and were employed by a business from Jefferson County, south of St Louis. They have not come forward publicly.
The comment on the video largely matches those of residents of the apartment complex where the shooting occurred, who said Brown was surrendering when he was killed.
A state grand jury and the Justice Department are investigating, but no decision on whether Wilson will face charges is expected until next month.
Benjamin Crump, the lawyer for Brown's family, said both workers came forward and told the family their account of the shooting.
He described the video as "of paramount significance."
"Not because they were not residents of Ferguson, and not because the construction workers were Caucasian, but because it is a contemporaneous recording of their immediate actions of what they had just witnessed," Crump said.
"It's the best evidence you can have other than a video of the actual shooting itself."
Ed Magee, spokesman for St Louis County prosecutor Bob McCulloch, said the workers are among witnesses who have been interviewed by authorities and are "part of the investigation."
The video likely would be admissible evidence before the grand jury along with the workers' testimony, said Peter Joy, a professor at Washington University School of Law in St Louis.
"The thing that strikes me is we actually have a film of what's going on and while it's hard to hear the construction workers say what they're saying, you have one construction worker putting his hands up in the air, which appears to be him demonstrating what he's seeing," Joy said.
Lori Lightfoot, a lawyer who previously worked as chief administrator for the Chicago Police division that oversaw officer-involved shootings, said the video could be significant but many questions remain: What was the vantage point of the workers? How far away were they from the shooting?
"Given the stakes, it's essential that all of these issues be tied down," she said.
