Thomas Matthew Crooks, the individual who attempted to kill former President Donald Trump, meticulously planned his attack and spent days preparing, according to a recent report.

In the 48 hours before the shooting, the 20-year-old took a series of actions to ready himself for the attack, CNN reported.

"He went to a shooting range where he was a member, and practiced firing,” a law enforcement official told the news outlet. The next day, he made a trip to Home Depot and bought a five-foot ladder. He later purchased 50 rounds of ammunition from a local gun store.

On the day of the Pennsylvania rally at which Trump was set to address the crowd, Crooks drove to the venue and parked his car close by with an improvised explosive device concealed in the trunk. The device as connected to a transmitter he carried on his person.

Upon arriving, Crooks climbed a nearby building using the ladder he purchased. Shortly after, he tried to shoot the former president, grazing him in the ear. The presence of the transmitter led authorities to believe he was planning a larger-scale assault. “That suggests the gunman may have been planning to set off an explosion remotely,” said a law enforcement official.

It’s unclear how Crooks assembled the explosive devices found in his car. Investigators parsing through his online search history haven’t found any indication of him researching how to make home-made explosives, law enforcement officials said.

The AR-style rifle Crooks used to fire on Trump was legally purchased by his father, Matthew Crooks. It was one of more than 20 firearms registered to the elder Crooks, which were kept at the family’s home, according to Pennsylvania State Police records reviewed by investigators, the official said. All of the guns were legally purchased.

The gunman and his father were members of Clairton Sportsmen’s Club, a gun club about a 25-minute drive from his house, and enjoyed going shooting there together, according to law enforcement officials. Rob Bootay, a lawyer for the club, confirmed in a statement that the younger Crooks was a member.

Matthew notified the authorities upon finding out that his rifle was gone, according to NBC News.

Police went to the Crooks home after his father called police saying he was worried because his son and his AR rifle were missing, three senior officials said. The call came after Crooks opened fire at the rally.

The authorities are still trying to ascertain a motive for Crooks’ actions. It was recently reported that officials managed to unlock his phone. However, no further information has been released.

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Interviews with those who knew the shooter have not appeared to turn up much that might explain his actions. A former high school counselor who knew the gunman told NBC News that he was “flabbergasted” after finding out he was the would-be assassin.

“Thomas was a quiet young man, an intelligent young man, but he did keep to himself,” former school counselor Jim Knapp said.

“He had a handful of friends. In the cafeteria, I’d sit down with him and I’d say, ‘Thomas, would you like me to get some kids over here?’ And he’d say, ‘Nope, Mr. Knapp, I want to be by myself.’ Which is fine,” Knapp said.

Knapp also indicated that Crooks “was a very good student” and that he usually “wasn’t in trouble.”

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“I go back and I think about it, and I say evil is in the world, and that’s what I believe happened with Thomas. He snapped. I believe that the devil and the evil really invaded his brain and that made him do what he did,” the counselor said.