(ABC 6 News) — New details have emerged in the assassination attempt of Donald Trump that took place on Saturday.

According to the FBI, Trump’s shooter, Thomas Crooks, was on law enforcement’s radar before the assassination attempt took place.

Investigators found a post on the gamer network, Steam, allegedly written by Crooks. The post read, “July 13th will be my premiere, watch as it unfolds.”

Meanwhile, new questions have emerged as to why 20 minutes passed between when Crooks was spotted and when he pulled the trigger.

“He should have been eliminated one way or another within one or two or three minutes,” said former FBI Agent Brad Garrett.

Crooks allegedly purchased an ammo box at Wal-Mart two days after Trump’s rally in Pennsylvania was announced. A search of his phone revealed he looked up the dates of Trump’s rally as well as dates for the Democratic National Convention.