CCTV footage of gunman Aaron Alexis
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Navy Yard shooting: CCTV shows gunman Aaron Alexis

The FBI has released footage of gunman Aaron Alexis during a deadly rampage at a Navy Yard in Washington.

He killed 12 people on 16 September, before he was shot by police in a running gun battle.

During a press conference, a spokeswoman said the 34-year-old believed he was being controlled by "extremely low frequency (ELF) radio waves".

Mark Mardell reports.

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