FBI releases video of Navy Yard shooter, Aaron Alexis

Posted: 09/25/13 at 2:55 pm EDT      Last Updated: 09/25/13 at 10:31 pm EDT

WASHINGTON (WHDH) -- The FBI released chilling video on Wednesday of an armed Aaron Alexis walking through the Navy Yard building just moments before he shot and killed twelve people last week in the nation's capital.

The video shows 34-year old Aaron Alexis entering the building with a backpack. He is then seen walking through hallways holding what appears to be a loaded gun.

Federal investigators say they've done their best to dig up all sorts of information and figure out what motivated Alexis.

"We have also partnered with FBI and NPD in conducting numerous interviews, obtaining records and conducting analysis of all data collected. This has been an exceptional collaboration interagency effort,” said Mike Monroe, special agent, NCIS.

Watch full video here:

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