TULSA, Oklahoma - A U.S. Food and Drug Administration investigation shut down a Tulsa cancer clinic Tuesday afternoon. Federal agents showed up at Camelot Cancer Care in south Tulsa around 11 a.m. and served a search warrant.

Investigators have been tight-lipped about why they were there, but a source tells us the FDA is looking into the center's use of Laetrile, and has a concern for the safety of its patients.

But one man speaks highly of Camelot and the natural chemical that he claims was saving his wife's life.

"Listen, my wife's dying, and we don't want to go with chemotherapy and radiation," said Sam Bass.

Bass said his wife, Yvonne, is fighting for her life. She's battling melanoma for the second time. She's been cancer free for five years, but he said the cancer has come back.

"She just couldn't tolerate the surgeries anymore, so we went natural, changed her diet," Bass said.

For the Basses, Camelot Cancer Care was the answer. It's an alternative cancer clinic that fights the disease with natural treatments.

"It's a natural route that I've done a lot of research on," Bass said.

He said his father-in-law took $13,000 out of his savings to pay for a 20-day treatment program. The couple came in from Oklahoma City. They've been in Tulsa for 8 days, and were planning to head back Tuesday night to finish the rest of her treatment at home. But as they left Camelot, FDA and FBI agents showed up.

Bass said they asked him to leave his wife's medication behind.

"My wife is dying of cancer and, for us, this was a hope and they took our hope away," Bass said. "They took our rights, in my opinion, for me and my wife to choose how to treat her."

Sam said his wife's treatment program did include Laetrile. The chemical, which is found in the pits of some fruits and nuts, is also listed on Camelot's website.

But, it's not approved by the FDA.

During the investigation, Michael McDonnough, 49, of Broken Arrow was arrested for pushing an officer while trying to sneak a computer out of the building. 

McDonnough was booked into the Tulsa County jail on a complaint of assault and battery on a police officer.  McDonnough is employed by Camelot but his role is unclear.

As for Sam, he said he didn't know Laetrile was outlawed until Tuesday, but even knowing, he said he doesn't care. Because without it, he said his wife may not survive.

"I just want my wife to get well. I've got three kids at home, they need their mom. I need my wife," Bass said.

An employee with Camelot said it hasn't been shut down, but will need to make some changes moving forward.

However the FBI said the clinic is temporarily closed.

As for the Basses, they said they can't afford to change treatments now.