New footage of the moment when the assailant who attempted to assassinate Trump was found dead has been released.

Body camera footage shows the moment police and Secret Service agents found the body of the potential assassin who fired at Donald Trump.

20-year-old Thomas Crooks had positioned himself on a rooftop just 130 meters away from the former president before carrying out his horrific attack at an outdoor rally in Butler, Pennsylvania on July 13.

The assailant, who fired a bullet that grazed Trump's ear and resulted in the death of one person and serious injuries to two others, was soon killed by Secret Service sharpshooters.

In the footage released on Tuesday, a suited man - likely a Secret Service agent - and heavily armed officers can be seen gathering around Crooks' body and discussing the incident.

The suited man asks one of the armed officers, "So this is the guy, huh?"

The officer responds, "Yes. The sharpshooter from Beaver County who spotted him and sent in the photos. That's him."

The officer's recognition of Crooks confirms that the Secret Service was aware of the presence of a suspicious individual before the shooting began.