As the grand jury in Ferguson, Missouri considered whether to indict police officer Darren Wilson over the shooting death last August of unarmed African American teenager Michael Brown, the Department of Homeland Security (DHS) was working on a plan to "plug" federal officers into protests to "perform surveillance" and "collect intelligence in the crowd."

The disclosure is contained in more than 700 pages of documents VICE News obtained from DHS in response to a Freedom of Information Act (FOIA) request, and comes just a couple of weeks before the one-year anniversary of Brown's death, which helped spark national debate about the targeting of African Americans by police.

It's unclear, however, whether DHS executed the plan. Some information in the documents was withheld on grounds that it would reveal law enforcement techniques, procedures, and trade secrets, or potentially endanger the life of an individual, DHS said.

Kade Crockford, the director of the American Civil Liberties Union's Technology for Liberty project, told VICE News that sending officers into protests "to spy on dissidents is both relatively routine and extremely problematic."

"The First Amendment protects our right to criticize the government and agitate for social and political change, and this kind of law enforcement activity directly threatens that right," she said. "DHS's choice to spend taxpayer dollars spying on today's black civil rights activists shows that federal law enforcement continues to view black people's demands for basic rights and equality as somehow threatening.

"Congress or inspectors general of the FBI and DHS should investigate how federal law enforcement agencies have been spending precious government resources keeping track of activists. The results of such investigations should be made public so we have a more complete picture of how and where the Feds are dedicating funds and staff to monitoring black dissidents in the wake of Ferguson."

Protesters raised concerns at the time on social media about the presence of DHS vehicles at the protests. It is not uncommon for DHS and other federal law enforcement agencies to keep tabs on protests, particularly in cities where federal buildings and parks are located (St. Louis has both). But it has become increasingly clear over the years, internal government documents show, that federal law enforcement also views such high-profile protests as a possible breeding ground for domestic terrorist activity and a good source of intelligence.

Watch VICE News' 'Talking Heads: A Look Back at the Violence in Ferguson.'

The deployment of DHS officers to Ferguson and St. Louis was a reunion of sorts. "Looks like we are working together again," one officer remarked to another in an email. "Long time since [Hurricane] Katrina. LOL."

The cache of documents, although heavily redacted, reveal that DHS had stocked up on batons and shields due to concerns that protests could quickly turn violent in the aftermath of the grand jury's decision. Officers who were being deployed to Missouri were required to go through new "training" to learn how to handle themselves if riots broke out. The documents also reveal that DHS suspected that its operational plans for confronting the protests would attract negative attention from the public and the media.

The fears of riots were so heightened that DHS officials barred officers from scheduling vacation and taking time off in order to make certain personnel could be present and on call in Ferguson.

In an attempt to thwart the release of information, an employee with DHS's National Protection and Programs Directorate distributed an email on November 11, 2014 reminding personnel to mark all electronic communications "for official use only" because of "recent events and FOIA requests." (Though "for official use only" is not an official security classification, government agencies use it as a protective marking to exempt documents from public disclosure.) DHS personnel were also instructed to be mindful of their own social media posts about the protests and Brown's death, as they could be a "hindrance or burden if the wrong thing is said/typed."

The emails also reveal that in anticipation of a grand jury decision, the deputy assistant director of the FBI's Security Division made a decision to deploy dozens of "FBI police officers" to St. Louis to "enhance the protection of the FBI St. Louis Field Office."

FBI police officers are different than FBI agents. The police officers are uniformed members of the bureau who are tasked with protecting FBI facilities; they have limited law enforcement powers.

"The deployed FBI police will only be responsible for the protection of their facility," said a November 6, 2014 email whose sender's name was redacted. But DHS also provided the FBI with a "short-term (30-day) Delegation of Law Enforcement Authority to provide the deployed FBI Police Officers with legal authority should they become involved in a law enforcement action."

The documents reveal that DHS received "intelligence" — largely based on a Fox News report — and subsequently investigated claims that Muslims had "co-opted" the protests in Ferguson.

"Have you seen this line of reporting before?" a Federal Protective Service employee wrote in a November 18, 2014 email. "Do you think Ferguson is becoming attractive to [redacted, though likely a reference to a terrorist group]? Any insight would be appreciated."

The Fox News report focused on how the Council of American and Islamic Relations (CAIR) was trying to raise awareness about the 2009 shooting death of Luqman Ameen Abdullah, an imam at a Detroit mosque. The right-wing think tank Center for Security Policy alleged in a report, which Fox News cited, that Muslim groups like CAIR had "ulterior motives" for joining in the protests.

The documents do not reveal how DHS followed up on the claim.

_Follow Jason Leopold on Twitter: _@JasonLeopold