BOSTON – Robert Weiss had been told repeatedly his rare, blistering skin disease was untreatable – until he found Dr. Abdul Razzaque Ahmed.

The Boston-area specialist’s alternative treatment put Weiss’ pemphigoid in remission, sparing him the severe side effects of long-term use of steroids, the common treatment for the disease.

“I can tell you that he saved my life,” said Weiss, a retired medical doctor and former dean of the School of Public Health at Columbia University, who now lives in Orono, Maine. He would have died if he had had to keep taking steroids, he explained.

It wasn’t until he was contacted by federal investigators years later that Weiss learned Ahmed had been deceiving Medicare to get treatment for him and other patients suffering from pemphigoid, a disease that was not covered by Medicare at the time.

“I certainly don’t believe he should have done what he did, but I’m grateful to him,” said Weiss, 89.

Ahmed pleaded guilty Monday to a single count of obstruction of justice and agreed to surrender $2.9 million in assets. In exchange, prosecutors agreed not to pursue 14 other more serious charges against him – including health care fraud – and said they would not seek prison time when he’s sentenced Feb. 4.

When Ahmed was indicted two years ago, authorities depicted him as a greedy businessman looking to squeeze as much money as possible out of Medicare, the federally subsidized health insurance program for the elderly and people with disabilities.

Patients have a different picture of Ahmed, who helped them get expensive treatments they would otherwise not have been able to afford. On Monday, federal prosecutors acknowledged Ahmed was helping many of his patients even as he broke the law.

Ahmed declined to comment Monday, but his attorney, Richard Egbert, said Ahmed treated patients from all over the world who were referred to him by other physicians because conventional therapies were no longer working and had caused harsh complications.

“He gave this treatment to people for the purest of reasons, to alleviate their suffering and save their lives,” Egbert said.

Prosecutors say Ahmed duped Medicare by submitting fake diagnoses for 24 patients so he could collect reimbursements for intravenous immunoglobulin treatments, which cost between $10,000 and $12,000 per month.

The treatments are used for a severe, life-threatening skin disease called pemphigus vulgaris and for pemphigoid, which is less serious, but still debilitating. Many in the medical community credit Ahmed with persuading Medicare to cover the treatments for both diseases, but pemphigoid was not covered until 2002, several years after Medicare began covering treatments for pemphigus vulgaris.

Prosecutors say Ahmed, 59, of Brookline, collected $5.4 million in Medicare reimbursements, in part by mixing blood samples to claim that Weiss and other patients with pemphigoid also had the more serious disease.

Weiss, who suffered from osteoporosis and cataracts because of his earlier steroid treatment, said he was unaware that Ahmed had submitted a dual diagnosis for him.

“I was shocked that he had falsified the diagnosis without telling me,” Weiss said.

Ahmed was indicted on 15 counts of health care fraud, money laundering, mail fraud and obstruction of justice. In his plea agreement, Ahmed admitted trying to cover his tracks after his medical records were subpoenaed by federal investigators in 2000 by submitting false lab reports and letters to the referring physicians of some of his Medicare patients.

He continues to practice medicine, but the judge noted that his guilty plea leaves him subject to possible disciplinary action from the state medical board.

Ahmed, who was born in India and became a U.S. citizen in the 1970s, was on the medical staff at New England Baptist Hospital and was an associate professor of oral medicine at the Harvard School of Dental Medicine. He ran his medical practice through a private Boston clinic he owned, the Center for Blistering Diseases.

Prosecutors began investigating him in 1997 after Medicare realized he was receiving millions in reimbursements for the IV immunoglobulin treatments.

People who have worked with Ahmed say he wasn’t driven by profit, but instead by a desire to help patients who would not have been able to afford the intravenous immunoglobulin treatments.

“He was very instrumental in getting pemphigus covered by Medicare, and all of this community has to thank him for that because nobody else was doing it. He basically did that alone for the betterment of the patients,” said Janet Segall, founder of the International Pemphigus & Pemphigoid Foundation, based in Sacramento, Calif.