Which scientists worked to determine the biochemical nature of transforming principle of Griffith's experiment?

Avery, McLeod and Mac Carty worked to determine the biochemical nature of transforming principle in Griffith's experiment. They discovered that protein-digesting enzymes (proteases) and RNA-digesting enzymes (RNases) did not affect transformation, so the transforming substance was not a protein or RNA. Digestion with DNase did inhibit transformation, suggesting that the DNA caused the transformation. They concluded that DNA is the hereditary material, but not all biologists were convinced.