Joseph F. Speyer, a molecular biologist whose work helped unlock the genetic code, died suddenly October 2 at his home in West Willington.

A professor of molecular and cell biology at UConn since 1967, Speyer held prior appointments as senior staff investigator at the Cold Spring Harbor Laboratory (1964-67) and as associate professor of biochemistry at the New York University School of Medicine (1957-64).

He earned his undergraduate degree in chemistry and his Ph.D. in biochemistry at the University of Utah (1955). His doctoral thesis research on the mechanism of action of the enzyme, aconitase, led to modification of the Krebs cycle.

Following two years of military service, he joined the biochemistry faculty at New York University. In addition to his work on the genetic code at NYU, Speyer is well known for his later pioneering work on mutator and anti-mutator genes that turned out to be mutations of the gene coding for the enzyme DNA polymerase. Analysis of these mutations led to the realization that the normal enzymes involved in DNA replication, and DNA polymerase in particular, played a role in correcting errors in DNA base pairing that otherwise would lead to the production of gene mutations.

Speyer was born in Eisenach, Germany, in 1926; he was the second child of a prominent attorney, Theobald Speyer, and his wife, the former Else Konrad. In 1939, under threat from the Nazi government, the family planned to evacuate to England. However, prior to departure, Mrs. Speyer and their daughter, Hannah, were forced by illness to delay their trip. The father, having already been arrested once by the Gestapo and expecting an imminent second arrest, fled to England with young Joseph and his brother, fully expecting to be followed by his wife and daughter. Unfortunately, World War II broke out within a few days of their arrival in England. The family was separated for the duration of the war.

Speyer graduated from the Gateway School in Leicester, England. This was followed by two years at London University while working part-time for a pharmaceutical company. After the war, he worked for the U.S. Army as a cryptanalyst, and emigrated to the United States in 1947.

Speyer is survived by his former wife, Anne Mattison; his long-time friend and companion, Ruth Piuck, and her daughter, Jean, of Newton, Mass; five children; a brother; a sister; and six grandchildren