The clinic’s Web site said treatments there include using microwaves to “heat” cancer cells, nutritional supplements, “ultraviolet blood purification” and colonics. Kurt W. Donsbach, a former San Diego chiropractor, opened the clinic in 1987. In 1988, the U.S. Postal Service ordered him to stop claiming that a solution of hydrogen peroxide could prevent cancer and ease arthritis pain. In 1997, he was sentenced in San Diego federal court to a year in prison for smuggling more than $250,000 worth of unapproved drugs into the United States from Mexico, according to court records. “I know of nobody who has engaged in a greater number and variety of health-related schemes and scams,” Dr. Stephen Barrett of Allentown, Pa., wrote on his Web site that tracks health fraud, www.quackwatch.org. Donsbach did not respond to repeated interview requests. However, on the Web site he defends his work and says that if the definition of “quackery” is the practice of nonconventional forms of healing, “I proudly proclaim myself a `quack!”‘ 160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set! SAN DIEGO – Like thousands of other desperately ill Americans, Coretta Scott King was apparently hoping for a medical miracle when she crossed into Mexico. For a half-century, patients have flocked to clinics south of the border for treatments that are shunned, prohibited or regarded as outright quackery in the United States. Among the treatments offered: blood transfusions from guinea pigs, colon cleansings, and the zapping of cancer cells with electrical current. Supporters say the clinics offer an alternative – and sometimes a cure – to people written off by U.S. doctors. Critics say the worst of the clinics do nothing but offer false hope while taking money from people when they are most vulnerable. “Were patients to return from Mexico cured and doctors saw the unbelievable, positive results, we would pursue it, but we just don’t see it,” said Dr. Jack Lewin, chief executive of the California Medical Association. “We don’t have patients coming back with miraculous cures.” AD Quality Auto 360p 720p 1080p Top articles1/5READ MORESanta Anita opens winter meet Saturday with loaded card On Thursday, the clinic where the widow of the Rev. Martin Luther King Jr. died this week was shut down by Mexican authorities. Mexican state officials said the clinic had been carrying out unproven treatments and unauthorized surgeries, employed people who were not properly trained, did not follow proper procedures for treating terminally ill patients, and failed to meet sanitary requirements. The clinic’s director has a criminal past and a reputation for offering dubious treatments. But its assistant administrator, Cesar Castillejos, defended its record and said he believed the government closed the clinic because of King’s death. King “wasn’t stupid,” Castillejos said. “She was very smart. She wanted an alternative.” The area around the border city of Tijuana is a hotbed for the clinics, with about 35 of them, according to Dr. Alfredo Gruel, health services director from 2000 to 2002 for the Mexican state of Baja California. King, who had advanced ovarian cancer, died before ever getting any treatments at the Santa Monica Health Institute, a beachfront compound in Rosarito, about 16 miles south of San Diego, doctors at the clinic said.