Beverly Hills, Calif. ? Plastic surgeon Frederic Corbin was intrigued last year when he saw an ad for a product that offered the same protein used in the wildly popular wrinkle treatment Botox – only much, much, cheaper.

“My initial reaction was, ‘Hmm, Botox now has some competition,”‘ recalled Corbin, who practices in Beverly Hills, Calif.

But when he received a vial of the botulinum toxin in the mail, he was puzzled by the warning: “For Research Purposes Only. Not for Human Use.”

He says he returned it and more or less forgot about it until he heard about four people last December whose mysterious paralysis was linked to the use of a Botox knockoff.

Authorities have found that dozens of doctors around the country bought unapproved botulinum, which in its raw form is one of the most potent neurotoxins on Earth. And investigative documents indicate that more than 1,000 people may have been injected with it.

The company accused of selling the unapproved toxin and marketing it as a Botox substitute goes on trial next month in federal court in Fort Lauderdale, Fla.

“We don’t know how dangerous it is,” said Dr. Thomas Rohrer, a Boston dermatologic surgeon who has written extensively about botulinum, which he describes as more powerful than cyanide.

Tucson, Ariz.-based Toxin Research International and owners Chad Livdahl and Zarah Karim, who are jailed awaiting the trial, are accused of defrauding people who thought they were getting a safe, approved Botox treatment.