Daniel P. Dukes (lost death photographs and possible footage of orca attack; 1999)
Daniel P. Dukes was the second person to be killed by Tillikum, the largest orca held in captivity. On July 6, 1999, he somehow bypassed security and snuck into SeaWorld Orlando. It is uncertain what his exact time of death was, but he decided to go skinny dipping in Tillikum's sleep tank. Tillikum then reportedly thrashed Dukes around in the tank and eventually killed him. The whale continued to play around with Dukes' body until the following morning when Tillikum was found parading Dukes' lifeless body on his back. The whale had reportedly bitten off Dukes' genitals, caused so many injuries that autopsy reporters were dumbfounded as to what the actual cause of death was and left his face in such bad condition that his funeral had to be held closed-casket.
It is possible that Dukes' death may have been captured on security camera footage. However, SeaWorld has declined to confirm this. There are confirmed pictures of his body being carried around by the whale taken by park employees for reference. However, the photographs (and the surveillance footage if it exists), have yet to surface as these are more than likely being held by the FBI, never to be given out for an official release.
This was also not the first, nor the last time; Tillikum killed someone. On February 20th, 1991, he killed a trainer named Keltie Byrne at the now-closed Sealand Of The Pacific in Victoria, British Columbia. His most recent kill would be Dawn Brancheau in 2010, whose death footage has also been left unreleased to the public. Tillikum continued to be seen at SeaWorld Orlando and was still being used in shows until his death in early 2017. The documentary film Blackfish details the story of Tillikum and can be viewed on Netflix.