Over four years ago, Santiago, 26, had a gun taken by Penuelas police in Puerto Rico and again more recently. In the PR incident, the reason for the confiscation wasn't made clear, and most likely was due to a complaint.
But on both occasions investigations were closed and his guns were returned to him in 2014 after a two year investigation.
Shortly after his guns were returned to him, he moved to Anchorage when in November of last year, he walked into an FBI office and reportedly told authorities that ISIS was influencing him and the government was attempting to control his mind by forcing him to watch ISIS videos.
His guns were again confiscated, this time by federal agents. He was given a mental health evaluation but was evidently deemed not to be a danger to himself or others and doctors believed he didn't need to be committed.
So Santiago was released and his gun returned to him on December 8th. So on January 6th, he was armed when he walked into the airport and began shooting. Whether or not the gun he used was the same that was returned is a moot point. He was allowed to have a gun, and the one he used was a Walther 9mm semi-automatic handgun.
Judging from what is known about Santiago, it's probable that he was influenced by ISIS but is also mentally ill. I would bet he suffers from schizophrenia but that needs to be determined. He appears to be eligible for the death penalty, but may get life in a mental institution if authorities see it the way I do at this time.
I am a strong Second Amendment advocate, but I also believe there needs to be better mental health screening as well as enforcement of gun laws. This guy should have been a red flag for anyone in law enforcement.