This week students and teachers at Marjory Stoneman Douglas High School begin the process of trying to get back to normal after the mass shooting that left 17 dead nearly two weeks ago. But while that difficult journey begins, we're learning more about the missteps that began long before Nikolas Cruz, the alleged killer, opened fire. According to the Broward County Sheriff's office, 23 calls were made about Cruz's behavior or his potential for violence— including a call from a Massachusetts tipster— and the FBI received at least two tips on alarming social media posts.

This comes on top of the shocking revelation from last week that the armed sheriff's deputy posted at Marjory Stoneman never went in the building while the shooting took place. The officer has since resigned and calls for the Broward County Sheriff Scott Israel to also step down are getting louder.

So how far should and how far can law enforcement go to prevent a tragedy? That question is being asked here, too, after a 22 year old woman was stabbed to death at the Winchester Public Library. Her alleged attacker and his violent behavior were known to police.  Jim Braude was joined by Ron Sullivan, Professor at Harvard Law School and Director of the Criminal Justice Institute at Harvard and Chelsea Police Chief Brian Kyes to discuss.