Crooks had flown the drone on a programmed flight path several times earlier in the day on July 13, to scour the Butler Farm Show grounds ahead of the event, the officials said. The discovery has raised more serious concerns over the reliability of the security services, the outlet notes.
What else has been revealed?
The use of the drone was just one way in which authorities said Crooks had planned his attack.
The perpetrator came to Trump's rally with a pair of homemade bombs designed for detonation with remote control.
The authorities also found primitive explosives and a vest with three 30-round magazines in Crooks' car. This suggests that he probably "wanted to cause greater carnage", according to the article.
Crooks had also ordered several packages labeled "hazardous materials" to be shipped to his home in the past month. He also conducted online searches for Trump rally dates, and information on Biden and the Democratic National Convention.
On Saturday, a 20-year-old man tried to assassinate Trump at a campaign rally in the state of Pennsylvania, but the bullet from the gunman's AR assault rifle grazed Trump's right ear. US Secret Service agents killed the gunman moments after he was able to fire several rounds toward the stage, killing one spectator and critically injuring two others.
The FBI continues to investigate the shooting, but the suspect's motive remains unknown, according to US law enforcement.