House Oversight Committee Chairman James Comer (R-Ky.) on Tuesday subpoenaed Department of Homeland Security (DHS) Secretary Alejandro Mayorkas along with three other DHS employees and two Secret Service staffers as the House panel expands its inquiry into whether the Justice Department improperly tipped off the protective agency while investigating Hunter Biden over alleged tax crimes.

The six subpoenas serve dual inquiries, seeking information surrounding how the Secret Service as well as the Biden transition team was notified about plans to interview the president’s son, along with alleging improper conduct by the agencies as committees aim to get that information.

Beyond the details sought about the Secret Service’s discussions with the Justice Department, the subpoena includes demands regarding DHS’s Office of Legislative affairs and includes an allegation that DHS blocked the Secret Service from responding to a previous request for interviews regarding claims from IRS whistleblower Gary Shapley. 

Shapley, an IRS agent who previously led the investigation into Hunter Biden’s tax issues, testified that Secret Service headquarters was improperly tipped off about a planned Dec. 8, 2020, attempt to seek an interview with Biden, foiling those plans.

Following Shapley’s testimony to Congress, Comer, House Judiciary Committee Chairman Jim Jordan (R-Ohio) and House Ways and Means Committee Chairman Jason Smith (R-Mo.) on June 29 sent Secret Service Director Kimberly Cheatle a request for testimony from several Secret Service employees regarding claims from Shapley.

In letters to Mayorkas and Cheatle alongside the subpoenas Tuesday, Comer said that his committee had learned that the DHS Office of Legislative Affairs had “instructed the Secret Service to withhold a response the Secret Service had prepared for the committees.”

In response, a DHS official said that “the claim that we obstructed or withheld a response is categorically false and these subpoenas are entirely without basis.”

“DHS was working to respond to this inquiry appropriately, including identifying the relevant information and individuals,” the official said.

Comer described several conversations between the Oversight Committee and Secret Service about their June requests. He said that the Secret Service on Aug. 25 had emailed that it intended to provide a written response by the close of business that day, but was waiting for final approval. 

Later in the day, Comer wrote, the Secret Service told Oversight Republicans in a phone call that DHS had instructed its legislative affairs office to not transmit a response. 

Several hours later, the agency sent the committee a response saying that it “was not able to identify any current employees with first-hand knowledge” of the alleged tipoff about the planned December 2020 Biden contact attempt. During a subsequent conversation days later, the Secret Service said that was not the originally prepared response.

“Investigators were never able to interview Hunter Biden during the criminal investigation because Secret Service headquarters and the Biden transition team were tipped off about the planned interview. This is just one of many examples of the misconduct and politicization during the Department of Justice’s investigation,” Comer said in a statement, adding: “The Department of Homeland Security is obstructing our investigation by muzzling the Secret Service from providing a response to Congress.”

Alongside Mayorkas, Comer subpoenaed DHS Director of Oversight in the Office of Legislative Affairs K. Shiek Pal; DHS senior adviser to the general counsel Stephen Jonas; DHS Office of Legislative Affairs Assistant Secretary Zephranie Buetow; Secret Service Assistant Director in the Office of Intergovernmental and Legislative Affairs Vincent Tutoni; and Secret Service Acting Special Agent in Charge in the Congressional Affairs Program David McKeown.

The DHS official said that the its process was misconstrued. 

“DHS works across all our components to respond to congressional inquiries in a uniform and accurate way,” the official said. “DHS was following standard procedures for the review and submission of materials to Congress, which have been utilized across multiple Congresses. These reviews are a normal and necessary step in the process to ensure protection of law enforcement sensitivities, matters relating to ongoing investigations, privacy and privilege issues, consistency in our responses, and more.”

The subpoenas request all December 2020 emails from DHS or Secret Service staff relating to the Biden investigation, as well as all emails and communications from June 29 onward dealing with the committee’s request regarding Shapley’s claims.

The alleged tipoff surrounding the planned attempt to show up at Hunter Biden’s home to seek an interview and possible “Hail Mary” consent search on Dec. 8, 2020 — as his father was preparing to take office — has been a key part of the House GOP’s claims of improper handling of the tax crimes investigation into him. 

In a May interview with staff from the Ways and Means Committee, Shapley said Justice Department officials planned only to coordinate with the Los Angeles-based Secret Service officials in advance of trying to speak with Biden.

But the evening before, Shapley said the FBI alerted Secret Service headquarters in Washington as well as the transition team preparing for his father’s inauguration.

“This essentially tipped off a group of people very close to President Biden and Hunter Biden and gave this group an opportunity to obstruct the approach on the witnesses,” he said.

Instead, investigators were punted to Biden’s attorneys, who said he “would accept service for any document requests, but we couldn’t talk to his client.”

“I can’t know for certain whether FBI’s advance notice played a role or not, but of the 12 interviews we hoped to conduct on our day of action, we only got one substantive interview,” Shapley said of the broader effort to conduct interviews in the case that day.

An FBI agent who was involved in the Biden investigation and spoke to the Oversight committee also complained about the advance notice, but much of the frustration stemmed from the notice provided to the transition team.

“I felt it was people that did not need to know about our intent [to interview Biden]. I believe that the Secret Service had to be notified for our safety, for lack of confusion, for deconfliction, which we would do in so many other cases, but I didn’t understand why the initial notification,” a former FBI agent involved in the case said when asked about the alert to the transition team.

Neither the agent nor Shapley, however, knew any details about who in the transition team was notified about the planned interview attempt.

The agent also said that it was unlikely that Hunter Biden, an attorney himself, would have agreed to speak to him and Shapley had they knocked on his door.

Rep. Jamie Raskin (Md.), top Democrat on the House Oversight Committee, has previously criticized the House GOP’s messaging surrounding the alleged tip-off, saying in a statement last month that they have featured “selective and distorted parsing of information” and noting that the former FBI agent working with Shapley said that he was aware of no political interference into the investigation.

—Updated at 3:59 p.m.