ST. LOUIS – The FBI is searching for the motive behind Saturday’s attempted assassination of former President Donald Trump.

We still don’t know a lot about the suspected shooter, 20-year-old Thomas Matthew Crooks. The FBI believes he acted alone and that he had little to no social media presence.

Another big question still unanswered is how the Secret Service allowed him to get so close to the rally.

The gunman was armed with a rifle and perched on a rooftop, just about 130 yards away from where Trump was speaking.

The suspect had no criminal history and no known mental health issues.

The Secret Service is investigating how the shooter was able to get so close and into position without their agents noticing. The agency is under a lot of scrutiny for what’s being viewed as an inexcusable security breach.

A short time before the former president took the podium, local authorities were reportedly alerted to suspicious activity on the outside of the perimeter and were in the process of looking for a suspect.

President Biden has ordered an independent investigation into the shooting, urging Americans in an address last night to stay calm at a time when the country is so tense and divided.

The Governor of Pennsylvania has ordered flags to be flown at half staff in honor of the 50-year-old firefighter, Corey Comperatore, who was killed at the rally. His family says he died a hero, shielding his wife and two daughters from the gunfire.

Two other people attending the rally were seriously injured.

Meanwhile, former President Donald Trump arrived in Milwaukee Sunday night for the start of the Republican National Convention, about 24 hours after the attempt on his life Saturday at his rally in Pennsylvania.