What's the story?

A law enforcement official confirmed on condition of anonymity that Stephen Paddock, the gunman in last week's Las Vegas shooting, previously booked rooms at the Blackstone Hotel in Chicago, overlooking the park where the Lollapalooza music festival was held. The rooms had a clear view of the stage.

The official said it was unclear whether Paddock ever used the room or was in Chicago at the time.

When?

Paddock booked one room starting on Aug. 1, two days before the festival opened. He booked a second room on Aug. 3. The checkout date for both rooms was Aug. 6, the same day the festival ended.

Why does it matter?

The Lollapalooza music festival draws tens of thousands of concertgoers every year, with both high-profile musicians and attendees. The festival in August included artists Lorde, Chance the Rapper, Muse, and Arcade Fire. Former President Barack Obama's daughters Malia and Sasha were in attendance, along with Chicago Mayor Rahn Emanuel.

It's possible that the shooter may have initially intended to target a different festival, but changed his mind for reasons that are not immediately apparent.

Investigators are still trying to determine a motive for last week's shooting in Las Vegas, which was the worst mass shooting in modern U.S. history.