Luc Montagnier, a French virologist who discovered the virus that causes AIDS has died on Tuesday in the Paris suburb of Neuilly-sur-Seine, although the cause of death remains unknown.

Montagnier, 89, who shared a Nobel Prize in 2008 for discovering the HIV virus passed on with his children surrounding him.

The town hall in Neuilly confirmed that a death certificate for Dr. Montagnier had been filed there.

For all the glory that Dr. Montagnier earned in helping to discover the virus, today is known as H.I.V., in later years he distanced himself from colleagues by dabbling in maverick experiments that challenged the basic tenets of science.

Most recently he was an outspoken opponent of coronavirus vaccines.

The discovery of H.I.V. began in Paris on Jan. 3, 1983. That was the day that Dr. Montagnier, who directed the Viral Oncology Unit at the Pasteur Institute, received a piece of lymph node that had been removed from a 33-year-old man with AIDS.

Dr. Willy Rozenbaum, the patient’s doctor, wanted the specimen to be examined by Dr. Montagnier, an expert in retroviruses.

At that point, AIDS, or acquired immune deficiency syndrome, had no known cause, no diagnostic tests and no effective treatments.

From this sample Dr. Montagnier and his team spotted the culprit, a retrovirus that had never been seen before. They named it L.A.V., for lymphadenopathy associated virus.

In 1986, the virus that causes AIDS, known by Americans as H.T.L.V.-III and the French as L.A.V., was officially given one name, H.I.V., for human immunodeficiency virus.

Dr. Montagnier and Dr. Gallo shared many prestigious awards, among them the 1986 Albert Lasker Medical Research Award, which honored Dr. Montagnier for discovering the virus.

After his work with H.I.V., Dr. Montagnier veered into nontraditional experiments, shocking and infuriating many colleagues.

Montagnier was born on Aug. 18, 1932, in Chabris, France.

He married Dorothea Ackerman in 1961. They had two daughters, Anne-Marie and Francine, and a son, Jean-Luc.