(CNN) -- Jared Loughner's behavior was so disturbing that his father confiscated his shotgun and took to disabling his car every night to keep him home in the months leading up to an Arizona shooting rampage that left six people dead, according to investigative documents released Wednesday. Loughner's parents even went so far in the days and weeks before to tell their son he needed to get help "(be)cause his behavior is, um, been not normal," his mother, Amy, told investigators, according to transcripts of recorded interviews by investigators. The documents reveal vivid details about the events leading up to and surrounding the January 8, 2011, shooting during a meet-and-greet with U.S. Rep. Gabrielle Giffords outside a Tucson, Arizona, grocery story. Giffords, who was shot in the head, was among 13 people wounded in the shooting.
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NEW: Jared Loughner's parents took away his shotgun and told him he needed help
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NEW: Loughner bought six or seven boxes of ammunition, documents show
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NEW: He purchased a 9mm before Christmas 2010, investigators say
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NEW: Loughner ran from parents just before the shooting rampage, mom says
Gabrielle Giffords
Giffords
Many of the details surrounding the rampage are well known, from the heroic efforts to save @placeholder and others to the tackling of the gunman.
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@placeholder shooting survivor says she forgives Loughner, finds closure in guilty plea
Jared Loughner
Loughner
Jared Loughner
Loughner
Loughner
Loughner said he was feeling hot, so the deputy removed @placeholder's beanie and hooded sweatshirt.