The federal prosecutor investigating the riot at the Capitol said indictments could be issued this week. The FBI is working to find more than 400 suspects in the investigation.
Acting US Attorney for the District of Columbia, Michael Sherwin, said during a briefing on Tuesday that more than 135 people have been arrested so far in connection to the violent overthrow of the Capitol building on 6 January.
The Department of Justice expects the number of cases to keep going up as they make use of the huge amount of video and photographic evidence in addition to tips from the public.
The vast majority of the arrests have come from criminal complaints, Reuters reported. Criminal complaints are used temporarily to give the government time to build a case that will then be presented to a grand jury, as a suspect can not be convicted only on a criminal complaint in a federal court setting.
Only a few people have been indicted so far out of the hundreds of people who have been charged, many for minor offences such as trespassing. Others have been charged with more serious crimes such as assaulting a police officer and conspiracy. Many of the initial charges were minor but Mr Sherwin said they have added “significant” felony charges to most of the arrested suspects, the AFP reported.
Mr Sherwin said: “We’re continuing to build the evidence related to these charges. The individuals that were charged via the federal criminal complaints will then be indicted in the very near future to include this week.”
Charges like assaulting a police officer and disrupting a federal proceeding can lead to between 5 and 20 years in prison.
The FBI is looking into whether groups of people made plans to take over the Capitol before the riot. If some are found to have conspired to overthrow the government, they could be charged with seditious conspiracy. Mr Sherwin said he expected some suspects to face charges of this kind.
Three members of the far-right anti-government militia the Oath Keepers have already been charged with conspiring before the riot, but no indictment has been issued yet in this particular case.
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Mr Sherwin said: “It shows militia groups actively involved in planning and breaching the Capitol.”
He said the investigation would “reach a plateau" as the FBI has tracked down many of the suspects who posted images and videos of themselves on social media. The investigation is entering a deeper phase which involves “looking at the more complicated conspiracy cases”, Mr Sherwin said.
The investigations into the death of Capitol Police Officer Brian Sicknick and the bombs found at the DNC and RNC are ongoing, federal officials said.
The FBI agent leading the bureau’s investigation, Steven D'Antuono, said that they had received 200,000 tips from members of the public.