An investigation is continuing into the assassination attempt on former President Donald Trump, who appeared at the Republican National Convention in Milwaukee for a second time on Tuesday night with his ear still bandaged and with increased security evident around him.

The gunman’s motive in the Saturday attack on the president remains unclear four days after he opened fire at Trump’s campaign rally in Butler, Pennsylvania — injuring Trump and two others, and killing a rallygoer. The U.S. Secret Service is facing mounting questions about the security flaws that allowed the shooter to fire from a rooftop near the rally.

Eric Trump, the former president’s son, told CBS News his father doesn’t have stitches after he was shot, but has a “nice flesh wound.” He said his father’s hearing is fine and that he is “in great spirits.”

Details about the moments before the shooting are emerging. Cellphone video taken Saturday shows rally attendees pointing toward the shooter, Thomas Matthew Crooks, and trying to alert authorities to his presence — a full two minutes before the 20-year-old opened fire.

A sniper from a local tactical team deployed to assist the U.S. Secret Service at the rally took a picture of the gunman and saw him looking through a rangefinder minutes before he tried to assassinate the former president, a local law enforcement officer with direct knowledge of the events told CBS News. 

The sniper was one of three members of local tactical teams who were stationed inside the building that the shooter used in the attack, the officer said. The operations plan had them stationed inside, looking out windows toward the rally, scanning the crowd. The details about the three snipers were first reported by the local news outlet BeaverCountian.com. 

A federal law enforcement bulletin obtained by CBS News identified the gunman as “an apparent lone attacker.” The FBI is investigating whether he was a politically motivated homegrown domestic violent extremist.

The Department of Homeland Security’s inspector general is opening an investigation into the rally’s planning, and President Biden said he is directing an independent review of security and events at the rally to determine what went wrong.