Paul Duggan et al., Washington Post, January 27, 2014

Darion Aguilar, neatly clad in jeans and a dress shirt, strolled into a Rockville gun store Dec. 10 with a wad of cash and lots of questions. He wanted a weapon for home defense, he told the owners, who remember him as upbeat and courteous. He didn’t know much about firearms and asked for their help in picking one out.

“His whole demeanor was, he smiled, he was polite, he wasn’t aggressive,” said Cory Brown, a proprietor of United Gun Shop. Aguilar, then 18, told Brown and co-owner Dan Millen that he had been researching Mossberg shotguns. Could they show him a Mossberg?

So they got out a basic 500 model — “an entry-level” gun, Brown said — a pump-action 12-gauge that is easy for a novice to fire accurately in close quarters.

Saturday morning, 46 days ­after he left the shop with a $430 Mossberg 500 and two boxes of shells, Aguilar used the weapon at the Mall in Columbia, killing two employees of a clothing store and then himself as hundreds of frightened shoppers ran for cover.

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As Howard County police continue to investigate the shootings, they said the reason for the attack remains a mystery. They said they have found no connection between Aguilar and his victims, Brianna Benlolo, 21, and Tyler Johnson, 25, who worked in Zumiez, a store for skateboarders, snowboarders and surfers on the Maryland mall’s second level.

Two law enforcement officials, speaking on the condition of ­anonymity because the investigation is ongoing, said Aguilar kept a journal in which he described suicidal thoughts. When the young man’s mother reported him missing Saturday, they said, a police detective was sent to the home. He began reading the journal, but Aguilar’s mother demanded he stop.

Later, after authorities identified Aguilar as the shooter, police seized the journal. In addition to the references to suicide, it contains notes expressing hatred of certain groups, according to the officials, who did not elaborate in detail.

Aguilar, a 2013 graduate of James Hubert Blake High School in Silver Spring, shared a home with his mother in College Park, not far from Benlolo’s residence. But there’s no evidence the two were acquainted, police said.

Johnson, the other victim, lived in Mount Airy.

Police said mall surveillance video shows Aguilar lingering in the first-level food court for about an hour after he arrived at the shopping complex by taxi about 10:15 a.m. Then, toting a backpack, he rode up an escalator and apparently walked into a dressing room in Zumiez. Moments later, he emerged with the shotgun and opened fire.

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