Joe Exotic, the zoo founder who gained notoriety for his role in the hit Netflix documentary Tiger King, has been diagnosed with an aggressive form of prostate cancer, he said in a social media post.

In an Instagram post Exotic, whose real name is Joseph Maldonado-Passage, said he had received the news from his doctors.

“It is with a sad face that I have to tell you the doctors called me in today to break the news that my prostate biopsy came back with an aggressive cancer, I am still waiting on the results from other test as well,” Exotic said.

Exotic is serving a 22-year prison sentence after he was convicted of attempting to hire two men to kill an animal sanctuary owner, Carole Baskin.

In the post Exotic, who has maintained his innocence, asked that he be released from prison: “So I can go home and get treatment on my own or enjoy what life I have left with my loved ones!”

John Phillips, Exotic’s attorney, confirmed the news in a statement to CNN.

“The PSA test is a blood test used primarily to screen for prostate cancer. It was high. He finally obtained biopsies. They revealed cancer. Medical care is different in a prison environment and fewer options are available,” Phillips said.

In July a federal appeals court ruled that Exotic should serve a shorter prison sentence. According to the ruling, the court should have sentenced Exotic to somewhere between 17 and a half years and just under 22 years in prison, rather than between just under 22 years and 27 years in prison.

A second instalment of Tiger King, called Tiger King 2, is scheduled to be released on 17 November.

This week Baskin filed a lawsuit against Netflix and Royal Goode Productions, claiming the upcoming show used unauthorized footage of her and her husband, Howard Baskin.