Police are studying a journal seized from the house where Darion Aguilar lived with his mother for clues to what inspired his deadly weekend rampage at an upscale Maryland shopping mall.
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Howard County Police Chief William McMahon said Aguilar expressed “general unhappiness with his life” within the journal’s pages.
Aguilar, 19, was less than a year out of high school. He walked into Zumiez, a skateboarding shop, at the Mall in Columbia in suburban Baltimore Saturday and fired six to eight shots, police say – killing two and causing terror for hundreds of shoppers before turning the gun on himself.
His victims were employees Tyler Johnson, 25, and Brianna Benlolo, a 21-year-old single mother.
Police are still trying to determine whether the gunman knew either victim.
The Prince George's County Police Department said it received a missing persons report for Aguilar at about 1:40 p.m. Saturday, more than two hours after the mall shooting. Officers went to Aguilar's home to speak with his mother about 5 p.m. and saw Aguilar's journal. The portion the officer read made him concerned for Aguilar's safety, the department said.
Police began tracking Aguilar's phone and soon discovered it was at the mall.
Howard County Police Chief William McMahon said there has been speculation about a romantic relationship between the gunman and Benlolo, but investigators have not been able to establish that.
Neighbors and relatives spoke fondly of Aguilar Sunday. Ellis Cropper, a friend, called Aguilar “a good kid.”
“I don’t know what happened,” Cropper said.
A woman identifying herself as Aguilar’s mother spoke briefly by telephone with ABC News. She sobbed, saying her son was gentle and “never had any interest in guns.”
But police say he bought a shotgun last month – a 12-gauge Mossberg – and kept it hidden as a taxi cab dropped him off at the mall.
Authorities say surveillance tapes show him sitting and walking around for nearly an hour, blending in with hundreds of shoppers.
The gunfire lasted only moments, but sparked an afternoon of chaos.
As the mall reopens Monday, shoppers such as Tara Williams remain unsettled.
“I don’t bring my kids to malls because I have four little ones. I can’t save them all,” Williams said.
The mall’s reopening comes under increased security.
Zumiez chief executive Rick Brooks said when the mall reopens, there will be memory books to sign and visitors will be invited to float flowers in the mall’s fountain in memory of Benlolo and Johnson.
"Counselors have met with the store team," Brooks said in a statement Sunday. "The emotions are very raw and real — and as co-workers and friends, we are pulling together."
ABC News’ Dan Good and The Associated Press contributed to this report.