Ferguson, United States - US Attorney General Eric Holder has arrived in the violence-ravaged suburb of Ferguson and said the "eyes of the nation" are fixed on protests over the police killing of an unarmed black teenager.
"The world is watching, because the issues raised by the shooting of Michael Brown predate this incident," Holder said on Wednesday at talks with community leaders in the Missouri suburb, which has suffered violent racially-charged protests since the fatal shooting of 18-year-old Michael Brown by a white policeman on August 9.
"This is something that has a history to it and the history simmers beneath the surface in more communities than just Ferguson."
"On one side, people are saying you're rushing to justice, and on the other side, they're saying you're dragging this thing out.
Holder said that the justice ministry's "most experienced agents and prosecutors" were on the case. While federal prosecutors conduct their inquiry, local police and prosecutors had their own jobs to perform, he added.
Protesters rallied outside the prosecutor's office on Thursday to complain that the officer has not been charged in a case that has exposed simmering tensions between the suburb's mostly-black residents and mostly-white police.
The office began presenting evidence to a grand jury on Wednesday but prosecuting attorney, Bob McCulloch, said the process could last until mid-October as he balances demands for swift justice against the need for a thorough review of the facts.
"On one side, people are saying you're rushing to justice, and on the other side, they're saying you're dragging this thing out," McCulloch told reporters.
"We're going to present this as expeditiously as possible, but we are not going to present it in a half-hearted manner."
Outside the office, protesters daubed "No Support For Murder" and other slogans on the tarmac, demanded the prosecutor's removal and called for the arrest of the officer, 28-year-old Darren Wilson, who has been suspended with pay.
"They're taking forever for justice to be served," protester Monica Porter, 45, told Al Jazeera.
"If it'd been shown that you murdered somebody for no reason you should be in jail. Not sitting at home on your couch, collecting a check from the city of Ferguson, doing nothing."
Police have said Wilson fired during a fight with Brown, but witnesses said the teenager was shot as he held his hands up in a position of surrender. Protesters mimic the pose during rallies and chant, "Hands up, don't shoot."
Law enforcers have struggled to cope with a combination of peaceful protesters and looters who smash windows and torch buildings in violence that raises fresh questions about US race relations almost six years after Americans elected their first black president.
Police arrested 47 people on Tuesday night but said that Ferguson's streets were calmer than on earlier nights, when officers said they faced gunfire and Molotov cocktails.
Deploying the Missouri National Guard and police use of military-style weapons has been criticised as over the top.
Protesters left the prosecutor's office and promised a further night of demonstration despite dwindling attendance at the nightly rallies along West Florissant Avenue, a strip of pawn shops and fast food joints that looked downtrodden even before windows were smashed.
"Someday these protests are gonna fizzle out and those people in Ferguson are still gonna have to deal with police," Damon Davis, 29-year-old music producer, told Al Jazeera. "So when all the TV cameras go away, they need to have a way to police the police."
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