The US department of homeland security’s inspector general is investigating the Secret Service’s handling of security for former president Donald Trump on the day a gunman tried to assassinate him at a Pennsylvania rally.
The agency said on its website that the objective is to evaluate the service’s “process for securing former President Trump’s July 13 2024 campaign event”.
No date was given for when the investigation was launched.
The shooting has raised questions about how the gunman was able to climb onto a roof with a clear line of site to the former US president, who was injured.
US President Joe Biden has already directed an independent review of the security at the rally.
Secret Service director Kim Cheatle said the agency understands the importance of the review ordered by Mr Biden and would fully participate in it as well as with congressional committees looking into the shooting.
The 20-year-old gunman, Thomas Matthew Crooks, was able to get within 135 metres (442ft) of the stage where the Republican former president was speaking when he opened fire.
That is despite a threat on Trump’s life from Iran leading to additional security for the former president in the days before the Saturday rally.
A bloodied Mr Trump was quickly escorted off the stage by Secret Service agents, and agency snipers killed the shooter.
Mr Trump said the upper part of his right ear was pierced in the shooting. One rallygoer was killed, and two others were critically wounded.
Ms Cheatle said the agency was working to understand how Saturday’s shooting happened and to make sure something like it never does again.
The agency of roughly 7,800 staff members is responsible for protecting presidents, vice presidents, their families, former presidents, their spouses and their minor children under the age of 16 and a few other high-level cabinet officials such as the homeland security secretary.
Earlier, Iran rejected accusations it was involved in any plots to assassinate Mr Trump.
Officials in Tehran also cited legal action over the 2020 assassination of a revered general by US drone, the state-run IRNA news agency reported.
IRNA quoted foreign ministry spokesman Nasser Kanaani as saying Iran “strongly rejects any involvement in the recent armed attack on Trump or claims about Iran’s intention for such an action”.
Mr Kanaani added: “The Islamic Republic of Iran is determined to pursue legal action against Trump for his direct role in the crime of assassinating Martyr General Qassem Soleimani.”
Gen Soleimani was the commander of the Iranian Islamic Revolutionary Guard Corps’ Quds Force and was killed in a US drone attack in Baghdad in January 2020.
A threat on Mr Trump’s life from Iran prompted additional security in the days before Saturday’s campaign rally, but it was unrelated to the assassination attempt on the Republican presidential nominee, US officials said.
On Tuesday, Iran’s ambassador to the UN, Amir Saeid Iravani, rejected the accusations against Tehran as “baseless” and “politically motivated”.
