Representative Adam Schiff, the chairman of the House Permanent Select Committee on Intelligence, has hired a veteran prosecutor with experience fighting Russian organized crime to lead his investigation of the Trump Administration. Last month, according to a committee source, Daniel Goldman, who served as an Assistant United States Attorney in the Southern District of New York from 2007 to 2017, joined the committee’s staff as a senior adviser and the director of investigations.

The hiring of Goldman, who will be joined by two other former federal prosecutors on Schiff’s staff, underlines Schiff’s decision to conduct an aggressive investigation of the Trump campaign’s ties to Russia during the 2016 Presidential campaign. In the rough division of labor among the various committees in the House of Representatives, Schiff’s panel is tackling the most provocative and, so far, most elusive subject related to the President: whether so-called collusion occurred between the Trump campaign and Moscow. In public comments, Schiff has suggested that Trump’s interest as a private citizen in building a tower in Moscow led him to curry favor with Vladimir Putin, the Russian President. American intelligence agencies long ago concluded that the Russian government made significant efforts, through the hacking of e-mails and use of social media, to help elect Trump over Hillary Clinton. The question of whether the Trump campaign facilitated, assisted, or knew about these efforts has been at the heart of the investigation by the special counsel, Robert Mueller—and will also be central to Schiff’s inquiry.

Goldman seems well suited to lead this effort. As deputy chief of the organized-crime section of the Manhattan U.S. Attorney’s office, Goldman supervised the prosecution of more than thirty defendants accused of racketeering, gambling, and money laundering. During his decade in the office, Goldman convicted individuals associated with Russian organized crime of securities fraud and health-care fraud, and convicted leading figures in the Genovese crime family of racketeering and murder.

One of Schiff’s previous committee hires drew a critical comment from the President. Last month, Schiff hired Abigail C. Grace, who served as an Asia-policy staffer on the National Security Council during the early part of the Trump Administration. In response, President Trump tweeted that the Democrats were going “nuts” and that Schiff was “stealing people who work at the White House.” In response, Schiff pointed out that congressional committees often employ individuals with experience in the executive branch.

The conflict between Trump and Schiff dates back to well before the Democrat took over as the chair of the Intelligence Committee, after the midterm elections. In a tweet, Trump once rendered Schiff’s name as “Schitt,” and, in his recent speech at the Conservative Political Action Conference, the President bestowed the congressman with the nickname Shifty Schiff.

Goldman’s hiring comes amid a flurry of investigative activity by Democrats on Capitol Hill. Schiff and Representative Maxine Waters, the chair of the House Financial Services Committee, have agreed to coördinate an investigation of Trump’s long-standing ties to Deutsche Bank, which has paid multimillion-dollar penalties for facilitating the work of Russian money launderers. On Monday, the House Judiciary Committee, led by Representative Jerrold Nadler, revealed that it had demanded testimony and documents from eighty-one people and entities close to Trump relating to the issues of obstruction of justice and abuse of power. And, of course, Michael Cohen, Trump’s former personal attorney, gave damning testimony to the House Committee on Oversight and Reform last week. All of these investigations appear to be much closer to the beginnings of their efforts than their ends.