FORT LAUDERDALE, Fla. -- Investigators working with the Centers for Disease Control and Prevention have determined what caused the paralysis in four people who received Botox injections at a South Florida clinic.

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For two weeks, health officials have feared that four patients who received the injections were suffering from botulism. Tuesday, the Florida Department of Health confirmed three of four patients who became ill tested positive for botulism.

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Now, investigators say one of the four patients, Bach McComb, the founder of the clinic where the injections were administered, has business ties to two companies under investigation for supplying an unlicensed Botox knockoff.

An Arizona company, Powderz International, and its sister company, Toxin Research International, allegedly supplied McComb with the Botox.

Investigators say an unregulated vial of Botox could contain more toxin than indicated on the label, which could lead to botulism.

State health officials say they have an ongoing battle to root out such activity and they hope to learn more about this case with the help of the patients being treated for botulism.

"The individuals who could help us get to the bottom of this the quickest are eager to participate but only to a limited degree in this investigative process, because they can't walk us around and show us things and speak to us in great detail," said Florida Health Secretary Dr. John Agwunobi.

Health officials say botulism patients can be paralyzed for up to a year until the toxins are flushed from their systems.