The top watchdog for the Department of Homeland Security altered and delayed investigations at the request of senior administration officials, compromising his independent role as an inspector general, according to a new report from a Senate oversight panel.

Charles K. Edwards, who served as acting DHS inspector general from 2011 through 2013, routinely shared drinks and dinner with department leaders and gave them inside information about the timing and findings of investigations, according to the report from an oversight panel of the Homeland Security and Government Operations Committee.

A year-long bipartisan investigation by the panel also found that Edwards improperly relied on the advice of top political advisers to then-Homeland Security Secretary Janet Napolitano and acquiesced to their suggestions about the wording and timing of three separate reports.

The Washington Post obtained an advance copy of the Senate document, which will be released to the public Thursday.

Edwards’s actions occurred while he was seeking President Obama’s nomination to be the permanent inspector general overseeing DHS, the third-largest government agency, with a $39 billion budget and more than 225,000 employees.

Read the document (Brendan Smialowski/AFP/Getty Images) Senate panel report on Homeland Security IG misconduct Report finds that Charles K. Edwards compromised his independent role as inspector general.

“We found that Mr. Edwards was a compromised inspector general . . . who was not exercising real oversight,” said Sen. Ron Johnson (Wis.), the ranking Republican on the subcommittee on financial and contracting oversight, which led the investigation of Edwards’s tenure. “Any report generated out of his office would be suspect.”

Edwards declined to comment through a department spokesperson.

Edwards, a 20-year federal career employee with expertise in computer engineering, resigned his office in December, three days before he was scheduled to appear at a Senate hearing to answer questions. DHS granted his request to be transferred into its office of science and technology, and the hearing was canceled.

Johnson and Sen. Claire McCaskill (D-Mo.), the subcommittee’s chairman, opened the investigation while looking into the hiring of prostitutes by Secret Service agents ahead of a 2012 presidential trip to Cartagena, Colombia. Whistleblowers alleged that Edwards had ordered them to remove derogatory information about the service and evidence implicating a White House staff member ; more staff members came forward to allege deletions and delays in other reports.

Several staff members said Edwards told colleagues, meanwhile, that he was the White House’s pick for the permanent job.

Investigators said they confirmed improper deletions and delays in several reports but did not reach a conclusion on the Secret Service-related allegations because the department declined to provide Edwards’s e-mails about the Secret Service report.

Napolitano, now president of the University of California system, said in a statement issued by her office several weeks ago that no changes were ordered in IG reports related to the Secret Service. “Neither Secretary Napolitano nor her staff ordered that anything be deleted in the Inspector General’s investigative report. Any suggestion to the contrary is false,” the statement read.

Napolitano said Wednesday that she could not comment on the Senate panel’s findings without reading the report.

One senior aide said Edwards ordered changes to a March 2012 report about Immigration and Customs Enforcement at the request of senior DHS officials, according to the Senate inquiry. The report dealt with complaints that senior DHS officials intentionally misled Congress and the public about a new program to identify illegal immigrants called Secure Communities, and whether local law enforcement was required to participate.

Edwards agreed to delay the release of the report at the request of a DHS official, Senate investigators said. The report was on Edwards’s desk on March 1 of that year, but he agreed to a request from John Sandweg, then DHS general counsel, not to release it until March 27.

The timing meant the report was not issued until after the director of ICE testified at a House hearing that month.

In another instance, the Senate report said, Edwards followed the suggestion of a top DHS official by adding information to a report questioning the effectiveness of advanced imaging screening by the Transportation Security Administration. Edwards’s chief investigator complained that the move was an effort to “derail our report and minimize our findings,” according to the Senate report.

Edwards agreed with the DHS official’s suggestion to classify the TSA report as “Top Secret/Secure Compartmented Information” — the highest level of classification — rather than the looser restriction of “Secret.” The label meant that members of Congress could read the document only if they had a reason to do so, made arrangements and reviewed it in a specially secured room.

The panel’s investigators said they could not confirm Edwards’s role in a report on Secret Service culture because — unlike in the other cases — his office declined to provide any related e-mails or correspondence. Edwards’s investigation concluded that the agency did not have a broad leadership or cultural problem in the wake of the Cartagena scandal.

The Senate investigation found that Edwards placed on administrative leave three people who questioned the Secret Service report deletions, including the office’s general counsel, who was on paid leave for eight months before getting another job. The federal office that reviews whistleblower complaints sided with the counsel’s argument that Edwards was retaliating against him for complaints the counsel made about Edwards’s conduct.

Edwards was particularly close to members of Napolitano’s inner staff and often communicated more with them than with his own senior leadership team, the Senate inquiry found. Before scheduled testimony in front of a House committee in March 2012, Edwards asked Sandweg, Napolitano’s top political adviser and acting general counsel, how Edwards should respond to questions from Congress about the best way to improve a department program, the report said.

Edwards also asked Sandweg to edit a memorandum of understanding that involved Edwards and to provide ongoing legal advice at work, investigators said. “I really need some legal help,” Edwards wrote in one e-mail to Sandweg. “Please help me for the next four months.”

Federal law requires inspectors general to remain independent of the agencies they oversee and to seek legal advice only from their own counsel or another IG’s counsel. Edwards told Senate investigators he didn’t trust his staff counsel.

The Senate report said Edwards conferred regularly with both Sandweg and Noah Kroloff, Napolitano’s chief of staff, at the same time he was allegedly pushing to delete embarrassing information from the Secret Service report. Kroloff has close ties to Mark Sullivan, the Secret Service director at the time of the inquiry, and left the department to co-found a private consulting company with him.

Kroloff declined to comment through a spokesperson, saying he had not seen the report. Sandweg, who resigned in February as acting director of Immigration and Customs Enforcement, also said he could not comment without seeing the report.

Senior officials in the inspector general’s office said they were not aware of Edwards’s private communications to DHS. Edwards told the Senate there was nothing improper about such updates.

A new DHS inspector general, former federal prosecutor John Roth, was confirmed by the Senate last month.

DHS spokesman Peter Boogaard said in a Wednesday statement that Homeland Security Secretary Jeh Johnson “believes in and values the critical role the IG plays in this department” and that he is confident in Roth’s new leadership of the office.

Responding to the Senate report on Thursday, Roth said that “this report, which examines a challenging era for DHS-OIG, contains valuable insights that my office will be taking into account as we move forward with our oversight mission.”