The Secret Service has been roundly criticized over its failure to prevent a gunman from opening fire on former President Donald Trump and killing one of his supporters.

However, stunning documents show that the agency also failed to uncover another deadly plot on January 6, 2021. 

Pipe bomb went undetected ahead of Kamala Harris' visit

As National Review noted, a report from the Department of Homeland Security's Office of the Inspector General (OIG) was released last week, and it detailed how then–Vice President-Elect Kamala Harris came within 20 feet of a "viable" pipe bomb.

The 81-page document explained that an unknown individual placed the explosive device in a bush outside of the Democratic National Committee (DNC) building in Washington, D.C. late on January 5.

The Secret Service's site agent later had a pair of canine units conduct sweeps of the building between 8:30 and 10:30 a.m. on January 6. 

While the site agent did not order a sweep of the building's exterior, one was nevertheless conducted. Yet although the exterior sweep covered the garage-entrance ramp to the building and adjacent areas, the bush was missed. 

No instructions were given on where to search

The OIG report pointed out how other Secret Service officials later indicated that the bush should have been included in an exterior sweep.

This oversight was attributed to the Secret Service having not requested the presence of a site coordinator, something which resulted in the canine units not being given specific instructions regarding where to search.

What's more, there was no explosives team on site to provide the canine teams with support, a fact that reportedly surprised the site agent.

"Two USCP plainclothes agents who were searching the DNC building after a similar device was discovered at the Republican National Committee building ultimately discovered the pipe bomb 1 hour and 40 minutes after the Vice President-elect’s arrival," the report read.

"The two USCP agents notified the Secret Service, who then evacuated the Vice President-elect from the DNC building," it added.

FBI has been unable to identify bomber

In addition to planting a bomb at the DNC's headquarters, an additional pipe bomb was also left outside of the Republican National Committee's building as well.

The #FBI has released a video of the person who placed pipe bombs placed near Capitol Hill between 7:30 p.m. and 8:30 p.m. on January 5. If you recognize this person’s gait, body language, or mannerisms, submit a tip at https://t.co/iL7sD5efWD. Tips can remain anonymous. @FBIWFO pic.twitter.com/tCqM6ipVZz

— FBI (@FBI) March 9, 2021

The FBI still has yet to identify the person responsible for leaving both explosive devices despite a years-long investigation and offering a half-million dollar reward for information.