Thomas Matthew Crooks had posted a chilling online message foreshadowing his plans before attacking former President Donald Trump at his rally in Butler, Pennsylvania.
"July 13 will be my premiere, watch as it unfolds," the 20-year-old would-be assassin, allegedly wrote on Steam, a popular online platform for gamers, reported Fox News.
Crooks reportedly also had images of both Donald Trump and President Biden on his phone and had searched the dates for the Democratic National Convention and Trump's Pennsylvania rally, The NYPost reported.
Investigators are analysing the shooter's phones and computer to determine the motive behind the assassination attempt. While they have explored the gunman's search history, they have not yet determined his political affiliation, despite his registration as a Republican.
The shooter reportedly had two cell phones, one found near his body and another at his home with only 27 contacts.
Law enforcement sources report that snipers spotted Crooks on a roof with a rifle at 5:52 pm, but he didn't start firing until 6:12 pm. This means a 20-minute delay occurred between the time Crooks was first seen and the start of the shooting.
After Crooks fired at Donald Trump, the Secret Service shot him dead within 26 seconds. The former president survived with just a minor injury to his ear.
The gunshots, fired by an AR-style rifle, killed a 50-year-old father of two girls and injured two others.
Sources told the NYPost that Crooks was identified as a person of interest a full hour before the shooting occurred. He had driven to Trump's rally on Saturday with a bunch of suspicious items in his car – a remote control transmitter, a detonator and an improvised metal explosive device connected to a receiver in his trunk – which suggested that he may have planned to cause a distraction or a diversion.
In the days leading up to the attack, Crooks visited a shooting range, and also stopped at Home Depot and a gun store, where he purchased 50 rounds of ammunition and a 5-foot ladder.