Joe Exotic's former director Rick Kirkham has claimed the Tiger King star injected zoo staff members with ketamine when they fell sick.
Speaking on the Investigation Discovery channel documentary The Truth Behind Joe Exotic: The Rick Kirkham Story, he accused Exotic of targeting workers who had coughs and colds with the powerful anaesthetic - ketamine hydrochloride.
Kirkham says the drugs were meant for animals but were instead given to humans.
"I saw Joe giving animal drugs to the humans working there.
"When they'd get a cough or a cold, he'd go grab ketamine, an animal tranquilliser, and shoot them up with that.
"I realised everyone who worked at the zoo was some kind of misfit.
"He portrayed himself as this animal lover and caretaker of animals. But after he became comfortable with me, he started to do things that were wrong."
Kirkham's side of the story will play out in the new special for the true crime channel, and will track his and Exotic's professional relationship, including how it went sour.
The director also accused 57-year-old Exotic of shooting a woman's horse and having it chopped up to feed his tigers.
"An old woman had a horse and she pulled up.
"She was really upset and said 'can you please take care of my horse he needs to go out to pasture'."
Kirkham said that "unbelievably cruel" Exotic agreed to look after the sick horse but as soon as its owner left, he pulled out his revolver and shot it before having it chopped up and fed to his tigers.
Exotic, who is currently serving 22 years' jail for a series of animal abuse charges, is currently seeking a presidential pardon for his crimes.