“All he cares about is his gun.”

“He could be a school shooter in the making.”

Those were among the concerns expressed in calls to law enforcement about Nikolas Cruz, who is suspected of shooting 17 people dead at Marjory Stoneman Douglas High School in Florida. Yet so many red flags triggered no legal action. How is that possible? Guest: Richard A. Oppel Jr., a national correspondent for The Times. For more information on today’s episode, visit nytimes.com/thedaily.