People who lost relatives to deadly reactions from the blood-thinner heparin recounted their loved ones in an emotional testimony before a congressional panel Tuesday, expressing their anger at the same time about the failure to ensure the drug’s safety.

LeRoy Hunley of Toledo, Ohio, described how he lost both his 65-year-old wife and his 47-year-old son within weeks of each other. Both were suffering from a genetic kidney disease that required constant dialysis, for which heparin is routinely used.

“As Christmas music softly played in the background, we each said our goodbyes. Then my wife and love of 48 years drifted away,” Mr. Hubley said, breaking down in tears, the Associated Press reports.

He had no idea for weeks after their deaths that his wife, Bonnie and son, Randy, had been given contaminated heparin.

“Now I am left to deal not only with the pain of losing my wife and son, but anger that an unsafe drug was permitted to be sold in this country,” he said.

Colleen Hubley, a dialysis nurse, was also present at the hearing on Tuesday. She recounted how her husband, Randy, came home from a dialysis treatment experiencing diarrhea, abdominal pain and breathing problems. He died the following night after she desperately tried to save his life with cardiopulmonary resuscitation.

“We were certain that no matter what came our way we could handle it together. Despite our hope, this man died while I did CPR on him, powerless to save him. I watched my husband and my best friend slip away before my eyes. I never thought the lifesaving medication we were relying on could be contaminated,” she said.

Contaminated heparin has been connected to 81 deaths and 785 severe allergic reactions, according to Rep. Bart Stupak, D-Mich., chairman of the House Energy and Commerce subcommittee on oversight and investigations.

The heparin, made from ingredients imported from China and used in dialysis and other treatments, has been recalled by Baxter International and the U.S. Food and Drug Administration has blocked imports from the Chinese company.

It was further discovered that the heparin was contaminated with oversulfated chondroitin sulfate, a chemical that mimics heparin but is cheaper ($900 compared with $9). Moreover, it is believed that the contamination was intentional.

“FDA’s working hypothesis is that this was intentional contamination, but this is not yet proven,” Dr. Janet Woodcock, director of the FDA’s Center for Drug Evaluation and Research, told the panel in her prepared testimony.

David G. Strunce, chief executive of Scientific Protein Laboratories, the company that supplied contaminated heparin material to Baxter, which manufactured and distributed the finished drug, believes the same thing, saying the contamination “seems to us an intentional act upstream in the supply chain.”

 “We are alarmed that one of our products was used in what appears to have been a deliberate scheme to adulterate a life-saving medication and that people have suffered as a results,” Robert Parkinson, CEO of Baxter International testified Tuesday.

Baxter sold about half of the U.S. supply of injectable heparin before the recall. APP Pharmaceuticals Inc. of Schaumburg, whose products remain on the market, produced the other half. All heparin being imported into the U.S. is being tested for the contaminant and the FDA says heparin currently on the market is safe.