The Department of Homeland Security’s (DHS) independent watchdog announced on Wednesday it is opening an investigation into security lapses that led to the attempted assassination of former President Donald Trump during a weekend rally.

The probe will “evaluate the United States Secret Service’s (Secret Service) process for securing former President Trump’s July 13, 2024 campaign event,” the office of the DHS inspector general said in statements posted to its website. The Secret Service agency is a department within DHS.

US President Joe Biden said on Monday that he directed an independent investigation into the security at Saturday’s rally “to assess exactly what happened.” The results of the probe will be shared publicly, said Biden.

It is unclear when the DHS probe was launched and if the review announced by the inspector general is the same one Biden ordered.

Law enforcement has identified the suspected shooter as Thomas Matthew Crooks, 20, from the state of Pennsylvania.

Crooks was fatally shot by a Secret Service agent after he opened fire from a nearby roof outside of the Butler, Pennsylvania venue where Trump was addressing supporters ahead of November’s national election.

Authorities have yet to determine a motive for the shooting but it has raised serious questions about security preparations for the gathering.

The shooting injured the former president, killed one spectator and critically wounded two others. Trump was seen being whisked off the stage by Secret Service agents, his face bloodied after it appeared that he was grazed by a bullet.

He later said he was shot in the ear and appeared at the ongoing Republican National Convention in Milwaukee, Wisconsin, with a bandage covering his right ear.

The Secret Service is tasked with ensuring the security of presidents and vice presidents, both former and current, as well as presidential nominees during election years.