Civil rights attorney Benjamin Crump, who represents the Brown family, slammed the grand jury process as "unfair" prior to Monday's announcement.
"The process is completely unfair," Crump told ABC News. "I just think this process is unlike anything I've ever seen in my 20 years of practice. We don't think it's fair."
Since Brown's death, protesters have taken to the streets daily demanding justice in the form of Wilson's arrest.
Immediately after the incident there were violent outbreaks and looting in Ferguson, which resulted in arrests and forced several businesses to close after being vandalized. On Aug. 17, 11 days after Brown was killed, some protesters burned down the QuikTrip gas station where a video surveillance tape showed him stealing a box of cigars before his altercation with Wilson.
For weeks, law enforcement and local residents have been bracing for a repeat of the riots after the grand jury announcement, due to early reports that Wilson would be cleared.
Ferguson Mayor James Knowles previously said authorities must "prepare for the worst" when the announcement is made.
"We are getting prepared for war," resident Ronald Ward, 33, told CBS News. "And that's just crazy."
Last week, Nixon declared a state of emergency in Ferguson and again activated the National Guard in preparation for a grand jury's verdict.
Some critics previously expressed concerns regarding McCulloch's handling of the case and even called for his removal. The veteran prosecutor's police officer father was killed in the line of duty when he was still a child, however, he previously insisted he is not biased.
"He has been involved in these type of cases before and has always been fair and open and will continue to be," Ed Magee, a rep. for McCulloch, said previously.
Brown's family previously said that regardless of the grand jury outcome, Wilson will be punished by God for "murdering" the teen.
"It's murder and they will feel and see the wrath of God's vengeance come upon them in a mighty way, just as He promised all who do evil in His sight," Sheryl Davis, Brown's aunt, told The Daily Mail.