Following a string of lawsuits and eventual action by the Federal Trade Commission, she relocated to Tijuana, Mexico, where she ran the Century Nutrition clinic.

Clark's claims and devices have been dismissed by authorities, ranging from the United States Federal Trade Commission and Food and Drug Administration to CAM figures such as Andrew Weil, as scientifically unfounded, "bizarre",[3] and potentially fraudulent.

From 2002 until her death she operated the Century Nutrition health clinic in Tijuana, Mexico, where her focus was primarily on late-stage cancer patients.

Clark and her son Geoff separately owned businesses her patients and others used, including a restaurant, her self-publishing company, and a "self-health" store that sold her inventions.

She asserted that eliminating these organisms from the body using herbal or electrical means while removing pollutants from the diet would cure all diseases.

"[14][15] Nonetheless, Clark advocated for the use of her methods as a substitute for standard medical care: Does this mean you can cancel your date for surgery, radiation or chemotherapy?

An investigator for the Indiana Department of Health and a deputy attorney general visited her office incognito as part of a sting operation.

[18][19][20] Six years later, in September 1999, Clark was located and arrested in San Diego, California, based on a fugitive warrant from Indiana.

Her lawyer protested the long delay before her arrest, but a prosecutor implied that she fled Indiana "when she learned that she was being investigated by the state," and the local police department had limited resources to devote to finding her.

The judge's verdict did not address the merits of the charges but only the issue of whether the delay had compromised Clark's ability to mount a defense and her right to a speedy trial.

In June 2001, the Mexican authorities announced that the clinic would be permitted to reopen, but was prohibited from offering "alternative" treatments.

Hence if patients do not apply her method consistently and their disease continues to progress, they run the risk of attempting to blame themselves for this, rather than Clark's treatment which is ineffective, as viewed at present.Prominent alternative medicine proponent Andrew Weil has written, "No studies have backed up [Clark's] bizarre claims, and it's unclear whether the cancer patients she's supposedly cured ever had cancer to begin with.

The article described a couple whose daughter with spinal muscular atrophy was treated for 10 months by Clark at a cost of approximately $30,000 without improvement.

Despite the cost and lack of improvement, the couple stated Clark insisted she was close to curing the child, and stopping treatment might endanger her.

[27][5][28] In memoriam, Oskar Thorvaldsson of the Self Health Resource Center, recalled that he first learned that she had been diagnosed by a doctor to have died from arthritis and spinal cord injury.