Secret Service officers stand post at a roadblock near the White House on May 14, 2015, after a person was arrested for allegedly trying to fly a drone nearby. (Shawn Thew/European Pressphoto Agency)

A government investigator told lawmakers Thursday that the failure of Secret Service supervisors to report a March 4 incident in which two agents drove into a White House bomb-threat investigation scene resulted from an agency culture in which lower-ranking staff fear retribution if they point out misconduct.

John Roth, inspector general for the Department of Homeland Security, said that his investigators found that at least four Secret Service supervisors who knew that the agents may have been drinking that night did not take the appropriate steps to alert the agency of potential violations of policy.

The two agents, Marc Connolly and George Ogilvie, were both ­senior-level veterans. Connolly, No. 2 on President Obama’s protective detail, outranked all of the officers and commanders on the scene. The agents were allowed to leave without taking sobriety tests.

“This was a point of failure,” Roth said, addressing members of the House Oversight and Government Reform Committee. “Everyone in the supervisory chain had a duty to report this either to me or the Secret Service office of professional responsibility. . . . They could have and should have reported this up the chain.”

Roth’s appearance coincided with the release of a report by his office, which found that Connolly and Ogilvie were “more likely than not” impaired by alcohol after five hours of drinking at a downtown bar that evening.

Homeland Security Inspector General John Roth waits to testify May 14, 2015, at a House Oversight and Government Reform Committee hearing on the Secret Service. (Yuri Gripas/Reuters)

Connolly and Ogilvie have denied drinking to excess that night. Larry Berger, an attorney for both men, said the report’s conclusions were “inaccurate and irresponsible.”

Secret Service Director Joseph P. Clancy last week placed the agents on administrative leave. Connolly informed the agency this week that he planned to retire.

Roth’s investigators found that Secret Service officers on duty at the time were shocked when the pair went through a checkpoint and drove into a temporary barricade. Both drove home that night in their respective government cars.

Roth said officers told investigators that the watch commander said to them that night that the two agents were “hammered” but that he would not order a sobriety test, because it would be a “career killer.” The watch commander reported the incident to his supervisor, who told his supervisor, Deputy Chief Alfonso Dyson, according to the IG report. But the commander did not include the matter in a daily log of significant events at the White House. Dyson told investigators that he spoke twice by phone that night with Connolly and that Connolly was concerned about the incident getting out, according to the IG report. House investigators who interviewed Dyson said he warned Connolly that night that the watch commander might “cause problems” by reporting the information, according to Rep. Elijah E. Cummings (D-Md.), the ranking Democrat on the Oversight Committee.

Dyson said in a statement to The Washington Post that he told Connolly in two conversations he needed to report the incident and that each time he said he would. Dyson said he  had “no reason to believe” Connolly, a senior executive with 27 years in the agency, would fail to report his actions.

Roth said that Chief Kevin Simpson, who oversees all 1,300 Secret Service uniform-division officers and was informed of the incident that night, told investigators he did not think it was part of his job to report possible misconduct by agents.

Editor's note: This video contains no audio. Surveillance video obtained by the House Oversight Committee from D.C. police shows a suspicious package being dropped off at a White House checkpoint on March 4. Shortly thereafter, Secret Service agents can be seen driving through the secured area during the proceeding investigation and nudging a barricade. (oversightandreform via YouTube)

Simpson told The Post in a written statement that he did not report Connolly’s actions because Connolly was a senior executive outside his chain of command and he had been told that Connolly planned to report the incident himself. “There are other articulable reasons that led me to believe the notification had been made,” Simpson said. “However, due to the pending internal review by the Office of Professional Responsibility, no further comment will be provided.”

Roth also disclosed an e-mail exchange in which Ogilvie and Connolly discussed whether they were in the clear. “All good?” Ogilvie asked. Connolly, who had just met with his boss, responded, “Muy bueno.” Ogilvie replied, “You are an angel.”