Washington (AFP) - Federal civil rights investigators will probe the fatal police shooting of a black father of five in Baton Rouge, Louisiana, officials said Wednesday, as the US city's mayor and police chief faced down calls to resign.
The death of 37-year-old Alton Sterling outside a convenience store was captured on cell phone video, triggering protests in the city and outrage nationwide over the latest case of alleged police brutality against black suspects.
The shooting came on the eve of a closely watched trial in Baltimore for an officer charged in the death of Freddie Gray, a black man who suffered a broken spine in the back of a police van.
Sterling was fatally shot in the early hours of Tuesday after an anonymous caller told police they had been threatened by a man with a gun, according to the police.
His family's lawyer said Sterling was merely selling CDs outside a convenience store, with the permission of the shop's owner.
Officials appealed for calm and promised a transparent investigation.
Calling the video "disturbing," Louisiana Governor John Bel Edwards said federal authorities will take over the investigation, led by the Department of Justice civil rights division.
"I have very serious concerns," Edwards told a news conference in Baton Rouge. "The video is disturbing to say the least."
Edwards said he spoke to the White House and planned to meet with faith-based community leaders to appeal for calm.
Baton Rouge officials identified the officers involved as Blane Salamoni and Howie Lake II. Both were placed on administrative leave, according to procedure, pending the results of the investigation.
- 'No cover-up' -
David Harris, a University of Pittsburgh law professor who studies police behavior and regulation, said it was "unusual for the Department of Justice to step in so quickly."
But he said the opening of a civil rights probe does not necessarily mean the Department will bring a case.
Federal law "requires not only showing of use of force that is excessive, but also that it was a willfull violation of the Constitution," Harris said. "That is the highest standard that any prosecutor has to take on in this country."
In Baton Rouge, emotions were running high. At an emotional press conference with relatives of the victim, the head of the city's chapter of the civil rights group NAACP, Michael McClanahan, called for the resignations of the police chief and mayor.
"What we are going to do today is rule out the one percent of bad police officers that go around becoming the judge, the jury, the executioner of people period but more specifically, innocent black lives," he said.
Both city officials responded with promises of transparency.
"We're an inclusive city," said Baton Rouge Mayor Kip Holden. "We have a wound right now. But we'll be healing and making the city and parish whole again."
Police chief Carl Dabadie said he is "demanding answers."
"There is a lot that we do not understand," Dabadie said, "It is our goal and our mission to make sure that a thorough, just, transparent and independent investigation be conducted into this incident."
- Video -
A graphic video shot by a witness and circulated online showed the altercation between the two officers and Sterling at 12:35 am (0535 GMT) Tuesday.
In the video, the officers ordered the tall and heavy-set Sterling to the ground but he remained standing.
The officers wrestled him to the floor, and while he was pinned down one officer pulled a gun and shot Sterling several times at close range.
ABC News published a second witness video late Wednesday, taken from a different angle, but which did not provide further clarity on the incident.
Police Chief Dabadie said Sterling had been armed.
- Body cameras -
Suspicion over police actions grew after reports emerged that the officers' body cameras fell off during the confrontation.
Authorities seized the convenience store's video surveillance system, which apparently captured the shooting, but have yet to release any footage.
Protesters, including friends and relatives of Sterling, gathered outside the store after the shooting, some blocking roads.
Holding up handmade signs, they chanted: "Black lives matter" and "Hands up, don't shoot."
- 'Legal lynching' -
Online reactions to the shooting grew Wednesday.
Actor Jesse Williams, whose televised BET Awards speech about police killings of black people was an internet sensation, responded on Twitter by asking for "a list of infractions punishable by spontaneous public execution."
African American civil rights leader Jesse Jackson called the shooting "a legal lynching."
On Instagram, Colin Kaepernick -- the quarterback for the San Francisco 49ers football team -- said it was a murder "at the hands of the people who they say will protect us."
Video footage of the incident can be viewed at: https://twitter.com/AyYoDex27/status/750499359339343872