( CNN ) -- U.S. Rep. Michael Grimm failed to report more than $ 1 million in sales and wages at a Manhattan restaurant he once ran , using unreported cash to pay workers `` off the books '' to `` evade taxes and keep more money for himself , '' a federal prosecutor said . Grimm , R-New York , pleaded not guilty on Monday in federal court in Brooklyn to 20 counts , including mail fraud , wire fraud , filing false tax returns , hiring unauthorized aliens and perjury . A former FBI agent who used to investigate fraud , Grimm wore a dark suit and was not handcuffed during the hearing . He was released on $ 400,000 bond , secured by his home in Staten Island . As conditions for his release , Grimm , 44 , must surrender his guns and passport . He told reporters that he would remain in office while fighting the charges . He 's up for re-election in November . `` I 'm going to fight tooth and nail ... until I am fully exonerated , '' Grimm said . One of his lawyers said previously that Grimm would be vindicated . Grimm stepped down from his position on the Financial Services Committee . In a letter to House Speaker John Boehner , Grimm asked to be removed from the committee until resolution of the unfolding legal matters . Boehner `` believes Rep. Grimm 's decision is appropriate under the circumstances , '' the speaker 's spokesman , Michael Steel , said . Indictment unsealed . An indictment unsealed on Monday after a probe of more than two years alleges Grimm lied to investigators about his taxes after leaving the Healthalicious restaurant to run for Congress . He `` never met a tax he did n't lie to evade , '' U.S. Attorney Loretta Lynch said . The charges relate to Grimm 's operation of Healthalicious from 2007 to 2010 , following his FBI tenure . He was elected to the House of Representatives in 2010 , representing Staten Island and parts of Brooklyn . He was re-elected two years later . Grimm , as an accountant , attorney , former Marine and ex-FBI agent , `` was poised for success as a small business owner , '' but `` made the choice to go from upholding the law to breaking it , '' Lynch said in a written statement . Much of the alleged scheme involved cash customers paid at the register , as opposed to credit or debit payments that created a paper record , Lynch said . The restaurant , in which Grimm had a 45 % partnership interest , did n't report some of the cash as income , Lynch 's office said . The restaurant also used cash to pay some workers -- some of whom did n't have legal status -- and then did n't report the payments to tax authorities , Lynch 's office said . `` Many employees received approximately half of their weekly pay in cash and the other half by check or through direct deposit into a bank account , while others received their entire weekly pay in cash , '' the statement said . By under-reporting the restaurant 's earnings and workers ' wages , the business was able to dramatically underpay its sales , income and payroll taxes , Lynch 's office said . Grimm calls case 'political witch hunt ' Grimm also is charged with conspiring to commit health care fraud and obstructing an official proceeding . Grimm said the investigation was `` a political witch hunt ... to assassinate my character and remove me from office . '' He told reporters that he felt `` somewhat relieved '' after the investigation because `` today at least I get to face my accusers . '' The indictment comes months after Grimm made headlines when he was shown on camera threatening to throw a reporter over a Capitol Hill balcony after an interview following the State of the Union address . In recent months , public attention also has focused on Grimm 's campaign donations after a friend and donor was charged with funneling illegal contributions to his campaign four years ago . The investigation into campaign finance is still ongoing , U.S. officials briefed on the matter have said . CNN 's Brian Vitagliano contributed to this report .
NEW : ' Grimm : ` ` I ' m going to fight tooth and nail ... until I am fully recovered '' U.S. Attorney : ' ` ` never met a tax he did n't lie to evade '' Grimm charged with fraud , filing false tax returns , perjury . Case centers on robbery of Manhattan restaurant .