Bought a ladder and...: What shooter Thomas Matthew Crooks did before Donald Trump assassination attempt

Thomas Matthew Crooks, the 20-year-old who attempted to assassinate former US President Donald Trump at a rally in Pennsylvania on Sunday and was gunned down by the Secret Service agents after the failed bid, has left the investigators with significant challenges in uncovering his motives.

The investigators are trying to piece together Crooks’ activities in the past 48 hours leading up to the attack to uncover the motive behind the failed assassination attempt.

A CNN report suggests that Crooks made a series of stops to stock up on ammo before the attack. According to the report, he practised firing at a shooting range a day just before the attack. He purchased a five-foot ladder and 50 rounds of ammunition from a local gun store in Bethel Park, Pennsylvania, on the day of the attack.

The report, citing sources, said Crooks used the same ladder to climb the building from where he opened fire at Trump.

The law enforcement officials told CNN that on the day of the attack, Crooks drove his Hyundai Sonata north to Butler, Pennsylvania, to mix in the crowd present at Trump’s rally. The enforcement officials also recovered an improvised explosive device wired to a transmitter he carried, suggesting a potential plan for a more destructive attack.

Crooks used an AR-15-style rifle, one of more than 20 firearms owned by his father.

The law enforcement officials, during the search of his computer and phone, did not find evidence suggesting political or ideological impetus for the shooting. The federal investigative agencies are treating the incident as a possible case of domestic terrorism, as explosive materials were found in Crooks’ vehicle.

Trump survived with a nicked ear during his rally in Pennsylvania on Saturday after Crooks opened fire at him. The attack left him with a bloodied face as the former president said the bullet pierced the "upper part of right ear".