Rep. Michael G. Grimm (R-N.Y.) surrendered Monday morning to federal authorities in New York as he faces multiple charges connected to a restaurant business he operated before entering Congress in 2011, according to sources familiar with the long-running probe into the lawmaker’s finances.

Grimm spent much of the weekend hunkered down, bracing for the unveiling of the federal charges, which were due to be disclosed after his surrender. He turned himself in to the FBI at an undisclosed location Monday morning and was taken to Lower Manhattan for processing. The charges stem from his ownership of a Manhattan health-food restaurant that has ties to an Israeli fundraiser who served as a liaison between Grimm and a mystic, celebrity rabbi whose followers donated more than $500,000 to Grimm’s campaign in 2010.

While the investigation has focused on Grimm’s fundraising, U.S. Attorney Loretta Lynch is expected to announce an indictment centered on his restaurant business, which Grimm launched after leaving the FBI in 2006, according to officials familiar with the investigation who spoke on the condition of anonymity to discuss the pending charges.

The state fined the Upper East Side restaurant, Healthalicious, $88,000 for not providing workers compensation. In a lawsuit against the company, workers accused the owners of not paying proper wages and sometimes giving out cash payments to skirt tax and business laws.

It is unclear whether federal prosecutors will eventually expand the charges to encompass Grimm’s campaign activities, but investigators have been moving on that side of the case against several key players, some with ties to the restaurant.

New York FBI spokesman Peter Donald declined to comment.

Healthalicious was run by a Grimm company that was connected to another company affiliated with Israeli fundraiser Ofer Biton. Last August, Biton pleaded guilty to filing false documents in 2010 when he sought an investor visa. The plea ended a standoff of several months, during which prosecutors asserted that Biton was not cooperating in their Grimm investigation.

Biton often served as a go-between for Grimm, a Roman Catholic, and followers of Yoshiyahu Yosef Pinto, a multi-millionaire celebrity rabbi with a strong following in the United States. Pinto is currently in discussions with officials in Israel over a plea deal in a case involving alleged bribery of police leaders there, according to Israeli reports. Pinto has congregations and charitable institutions in the United States and Israel, according to the Associated Press, and reportedly has close relationships with many business leaders, politicians and celebrities, including the Miami Heat’s LeBron James. Forbes Israel recently ranked Pinto as Israel’s seventh-richest rabbi, with a net worth of about $21 million.

The donations from Pinto’s followers proved crucial for Grimm in his 2010 campaign, his first political race, demonstrating to party leaders that he was a viable candidate. He narrowly beat the Democratic incumbent after a campaign that he devoted to his own biography, trumpeting his background as a Marine and an undercover FBI agent as a sign of his ethical standing.

On Friday, prosecutors with the U.S. Attorney’s Office for the Eastern District of New York unsealed an indictment against Diana Durand, a close friend of Grimm’s, alleging that the Houston businesswoman ran a straw-donor scheme that brought in more than $10,000 to Grimm’s 2010 campaign. The charges included lying to investigators in 2012 when they asked about her alleged reimbursement of Grimm donors.

While Grimm’s attorney has proclaimed the lawmaker’s innocence, the charges and the investigation have provided an opening for his Democratic opponent, former New York City councilman Domenic Recchia, who barnstormed the congressional district over the weekend. Recchia bounced around Staten Island and the southern end of Brooklyn, concluding the weekend at a charity event Sunday evening at the Yellow Hook Grille in Brooklyn. Upon his arrival, a waitress rushed up to Recchia and expressed interest in volunteering with his campaign.

Already inclined to support Recchia, Jessica Hauser told him that the arrival of new charges in the Grimm case “makes me extra inclined to volunteer.”

Recchia has tried to keep the campaign focused on kitchen-table issues, but he took indirect swipes at the congressman’s legal problems. “It’s very troubling what has transpired,” he said, suggesting that the criminal case will make it harder for Grimm to serve his constituents. “They want someone who is going to focus on them 100 percent.”

Despite Grimm’s legal predicament, Republicans are probably stuck with the embattled congressman on the ballot because the filing deadline for candidates passed two weeks ago. Some New York Republicans are angry about the timing of the charges, fearful that the case could get worse and leave them without a viable candidate in November. Grimm is the only Republican who represents any part of New York City.

The lawmaker’s attorney, William McGinley, denies that Grimm violated any laws and predicted that he “will be vindicated” when the case is concluded.

House Speaker John A. Boehner (R-Ohio) has not spoken to Grimm about the indictment, according to aides. Neither Boehner nor Majority Leader Eric Cantor (R-Va.) has commented about Grimm’s future. The National Republican Congressional Committee has declined to comment on the case. In some previous ethics cases, Boehner has called for lawmakers to resign or removed them from their committee assignments.

Grimm sits on the Financial Services Committee, which oversees Wall Street and the banking industry.

Despite the investigation, Grimm has remained a prolific fundraiser. Through March 31, he brought in more than $1.8 million for his reelection campaign and had more than $1.1 million in his account. However, the case has left a cloud over his political finances.

He paid $50,000 to McGinley’s law firm, Patton Boggs, in the last quarter, and his campaign reports show that he owes an additional $417,000 to the firm.