Baton Rouge - A steady stream of mourners on Friday filed past the coffin of Alton Sterling, the 37-year-old black man who was shot to death by police as he was pinned to the pavement outside a convenience store.The grieving paused in front of Sterling's open coffin, which was adorned with music notes and a smiling photo of the man. Sterling was selling CDs outside the store, as he had done for years, when he was killed by police responding to a call of a man threatening someone with a gun.One mourner wore a T-shirt that said "No Justice, No Peace" on the back of it. Another carried a poster board sign saying: "Black America I'm Sorry!!"Sterling's death was captured on cellphone video and circulated widely on the internet. His death, along with another fatal police shooting in Minnesota, sparked widespread outrage among many African-Americans over the treatment of blacks by police.Claire Carter was among those who came to the visitation inside the basketball arena at Southern University, a historically black college in north Baton Rouge. She, like so many others, said she wanted aggressive policing to end.Sterling's encounter with police "went too far" when officers tackled him and used a stun gun on him, she said. Police have said they found a gun in his pocket.Carter said she bought a rhythm and blues CD from Sterling about a year ago and took it out and played it again after his death.PlotSterling's death heightened tensions in Baton Rouge. About 200 protesters were arrested over the weekend and police said they had foiled an alleged plot to attack officers.Authorities said they discovered the plot after several men broke into a pawn shop and stole guns. One of the suspects said they did so to harm officers. Another one said he did it to sell the guns.Malik Bridgewater, 20, was scheduled to make his initial appearance in federal court on Friday. Police arrested Bridgewater and two other suspects on theft and burglary charges after eight handguns were stolen.Bridgewater told investigators his motivation was to sell stolen items for cash, an agent from the Bureau of Alcohol, Tobacco, Firearms and Explosives wrote in an affidavit filed on Thursday in federal court.State and local law enforcement officials said during a news conference on Tuesday that the stolen guns were part of a credible threat to harm police officers.The first suspect arrested in the burglary - 17-year-old Antonio Thomas - told police that "the reason the burglary was being done was to harm police officers".Baton Rouge Police Chief Carl Dabadie said threats like that justified an increased show of force at the demonstrations, as officers donned riot gear and used military-style vehicles after starting with a mostly reserved, low profile.Dabadie said Thomas didn't give any details about when or where a possible plot would be carried out.Police arrested a third suspect, a 13-year-old boy, on Monday. A fourth suspect remained at large on Friday.