Investigators find footage of Orlando gunman

Omar Mateen (CBS)
Omar Mateen (CBS)

Footage has emerged of Orlando gunman Omar Mateen after he was secretly filmed for a documentary on the BP oil spill.

The video comes as investigators delve into his past and question his wife over whether she knew about his deadly plans -- and among a slew of stories from survivors.

One of those to survive the attack on the gay Pulse nightclub, Richard Aitkin, was supposed to be spending Saturday night clubbing with his best friend.

Instead he spent three hours pinned to the night-club's bathroom floor as carnage unfolded around him.

"We could hear the shots getting closer and closer and then when he finally did, when the gunman finally did make it to the bathroom he fired some shots," Mr Aitkin explained.

He was hiding in the bathroom with nine others as gunman Omar Mateen went on his rampage.

"Bang bang, bang bang. After each shot I just kept wondering, 'Am I next? Is this going to hurt? Where is he going to shoot me?'"

Mr Aitkin's best friend was one of 49 people killed that night.

The ordeal finally ended when police swooped in.

Shortly before the attack, Mateen posted a chilling message on Facebook: "You kill innocent women and children by doing US airstrikes, now taste the Islamic State vengeance".

Investigators are now probing his background -- and have uncovered a video filmed five years ago for a documentary on the BP oil spill.

Mateen was working as a security guard, and said he was sceptical of the clean-up effort.

Investigators are also honing in on his wife, Noor Salman.

Police say they have surveillance video of her purchasing ammunition with Mateen -- and say she drove with him to the nightclub before the attack.

"At the end of all of our interviews -- however long that takes -- if someone is able to be charged in this investigation we will bring them to justice," FBI special agent Ron Hopper said.

If it's found Ms Salman knew about her husband's plans and didn't tell police -- she could be charged.