WASHINGTON () President Donald Trump on Sunday warned groups “on the Left” would be investigated after the killing of conservative activist Charlie Kirk, though he offered no details.

“If you look at the problem, the problem is on the Left. It’s not on the Right, like some people like to share the Right, the problem we have is on the Left,” Trump told reporters. “And when you look at the agitator, you look at the scum that speaks so badly of our country, the American flag burnings all over the place, that’s the Left. That’s not the Right.”

When questioned on whom he plans to investigate, he added, “We’ll see. We’ll be announcing.”

The president also suggested that some groups affiliated with the Left are already under investigation, without specifying which he was referring to.

“A lot of the people that you would traditionally say are on the Left,” he said when asked which groups will be investigated, adding, “they’re already under investigation.“

Authorities are still trying to learn the motive behind Kirk’s assassination at a college in Utah as his accused killer is expected in court Tuesday. Tyler James Robinson, 22, of Washington, Utah, was arrested on suspicion of aggravated murder and other felony offenses.

Investigators have spoken to Robinson’s relatives and carried out a search warrant at his family’s home in Washington, about 240 miles southwest of Utah Valley University, where the shooting took place.