Law enforcement oops for the day

Slate has an article by Ben Mathis-Lilley about cops, a little late to the party:

The FBI continued to monitor the behavior of failed Garland, Texas shooter Elton Simpson after his 2011 conviction for lying to investigators, and warned Garland police in the hours before his recent attack that Simpson might be targeting the Muhammad Cartoon Contest being held in the city. 

From CNN:

The FBI warned police in Garland about Elton Simpson's general interest in the controversial Prophet Muhammad cartoon event about three hours before Simpson and Soofi launched their attack, FBI Director James Comey said. Comey said the FBI had seen his social media comments referencing the event, but didn't know he had traveled from Phoenix, Arizona to Texas, and had no indication he was planning an attack. Comey made the comments at a meeting with reporters in Washington, DC.
Investigators say that Simpson interacted online with an ISIS-affiliated British national named Jenaid Hussein and an al-Shabab-affiliated American named Mohamed Abdullahi Hassan. It's not known whether anyone specifically encouraged Simpson to attack the event in Garland.
The FBI had re-opened its investigation of Simpson in March of 2015, Comey said. Its warning to Garland about Simpson was one of several such notifications about individuals who could be considered threats, and is not known to have been passed on to patrol officers before the attack.

Rico says an earlier warning might have changed things, but at least they both got whacked before they could carry out their attack... (And when are people gonna get it that Islamists have no sense of humor about the Prophet?)