Donald Trump is set to return to the site of his assassination attempt in Butler, Pennsylvania nearly three months after he was shot at during a rally.
In that time, investigations by US Senators and the Secret Service have tried to uncover the security failings which allowed 20-year-old Thomas Crooks to shoot eight times at the former president.
The BBC’s analysis editor Ros Atkins examines key questions about what happened on that day in July.
Produced by Michael Cox
Graphics by Mesut Ersoz