In 2011, Evan Ratliff, writing for The New Yorker, reported that Grimm had been the subject of an internal investigation into allegations that he abused his authority as an FBI agent in a nightclub in 1999.

[18][19] During his time with the FBI, Grimm spent two years posing as a small-cap stockbroker, uncovering white-collar criminals on Wall Street.

[20] After building a strong case for two years, he and the firm's partners were arrested together, at which point the police informed the group that they had been infiltrated by an undercover agent.

[28] He was endorsed by former NYC mayor Rudy Giuliani as well as Guy Molinari, a former U.S. Representative and Staten Island Borough President.

[31] Allegretti worked for the nonprofit Climate Group and cited his relationships with NYC Mayor Michael R. Bloomberg and former British Prime Minister Tony Blair.

[32] Grimm chose not to contest the Staten Island's party endorsement because of their "corrupt political culture" and "sham convention.

[citation needed] He received endorsements from high-profile Republicans, including Giuliani,[35] John McCain, Sarah Palin,[36] and former President George H. W. Bush, who applauded his service in the Gulf War.

On October 12, the Staten Island Advance reported that it had been receiving emails from the McMahon campaign attacking Grimm's business credentials.

[38] Grimm reportedly admitted in an interview with the Staten Island Advance that his former restaurant in Manhattan, Healthalicious, had been on the verge of bankruptcy, forcing him to sell his stake in it.

Grimm stated that the stimulus was a "huge waste" of taxpayer money and ineffective in generating job creation and economic recovery, whereas McMahon cited improvements in the state budget and renovations on the Staten Island Expressway and the Saint George Ferry Terminal as direct successes of the stimulus.

[41] He was challenged by Democrat Mark Murphy, a former aide to New York City Public Advocate Bill de Blasio.

[53] After the 2011 Tucson shooting, Grimm voiced support for "security-based situational awareness training", including how to spot suspicious people, when to run for an exit, and how to keep guards at close range.

House Leader John Boehner called his suggestions an "excellent idea" and indicated that security would be a major focus for Congress in 2011.

[54] Grimm voted in favor of the Pain-Capable Unborn Child Protection Act, a bill banning abortions after the 20th week of fertilization.

[61] In February 2011, as House Republicans were pushing for deep cuts in discretionary spending, Grimm wrote a letter to Eric Cantor saying he would vote against any budget that reduced aid to Israel.

"[64] According to a January 27, 2012, New York Times article, several followers of Orthodox Rabbi Yoshiyahu Yosef Pinto said Grimm's campaign had accepted questionable donations.

"[65] In June 2013, Grimm stated that he believed water fees should be waived for survivors of Hurricane Sandy who had been displaced from their homes.

Under New York City's Department of Environmental Protection rules, all homeowners are subject to a minimum charge of $1.19 per day, even if a home uses no water during a given period.

Residents who had been displaced from their homes for long periods of time received water bills over $500 for damaged, vacant properties.

Grimm called the bills "ridiculous," saying, "That's $500 these people could use to replace a washer or dryer or refrigerator swept out to sea during Sandy.

"[66][67] On January 28, 2014, NY1-TV political reporter Michael Scotto was interviewing Grimm in a balcony hallway of the U.S. Capitol building about the recently concluded 2014 State of the Union Address.

[74][75] According to Politico, in April 2014, Grimm became "the first sitting House Republican to stop denying the science that humans cause climate change."

"[76][77] In August 2012, the office of the United States Attorney for the Eastern District of New York said it was investigating Grimm's 2010 campaign.

[78] In November 2012, the House Ethics Committee decided to inquire into the campaign but agreed to "defer consideration" of it at the Department of Justice's request.

[84][85] On April 28, prosecutors unsealed a 20-count indictment charging that Grimm and others concealed over $1 million of the restaurant's sales and wages from both the U.S. federal government and the State of New York.

As part of the plea bargain, the other charges were dropped, but Grimm admitted to two of the offenses in the original indictment: knowingly employing people ineligible to work in the United States and lying in a 2013 deposition.

[88] On December 29, 2014, it was reported that after discussing the matter with House Speaker John Boehner, Grimm had changed his mind and would decline to take his seat for a third term.

On July 17, 2015, U.S. District Judge Pamela K. Chen suggested that Grimm's moral compass "needs some reorientation" and sentenced him to eight months in prison.