Trump also cast doubt on Comey's conclusions, just over a week after the Republican nominee praised the FBI director for announcing the review of the emails, which were discovered as part of the bureau's investigation into Anthony Weiner's sexting.
"Right now, she is being protected by a rigged system. It's a totally rigged system. You can't review 650,000 emails in eight days. You can't do it folks," Trump said, mischaracterizing the number of emails the FBI was reviewing for connections into the private server Clinton used as secretary of state.
The FBI took custody of electronic devices containing 650,000 emails in its investigation into Weiner, the estranged husband of Clinton aide Huma Abedin, but identified a smaller subset of those emails as linked to Clinton.
The FBI announced Sunday that its review of those emails had not changed the conclusions it reached over the summer, when Comey recommended no charges be filed after a year-long investigation into Clinton's use of a private email server, even though he called her handling of classified information "extremely careless."
Still, even as the FBI cleared Clinton for the second time, Trump argued that "the investigations into her crimes will go on for a long time."
"The rank-and-file special agents at the FBI won't let her get away with her terrible crimes," Trump said.
Trump served up his first response to the FBI's announcement on Sunday before a packed and rowdy crowd of supporters at an amphitheater in this Detroit suburb, where supporters cheered loudly and belted a raucous cry of "Lock her up! Lock her up!" as Trump addressed his rival's email controversy.
Trump will return to Michigan -- which hasn't voted for a Republican presidential nominee since 1988 -- once more before voters head to the polls on Tuesday, holding his final campaign rally in the state on Monday night.
Trump is trailing in the polls here, but advisers to the billionaire's campaign have argued that they see an opening to make inroads.
Former President Bill Clinton stumped in the state on Sunday as Democrats look to protect the state from falling in the Republican column, and the Democratic nominee herself will also hold a rally in Michigan on Monday.