Who revealed the biochemical nature of the transforming principle? How was it done?

(N/A) Oswald Avery,Colin MacLeod,and Maclyn McCarty ($1933$-$1944$) worked to determine the biochemical nature of the 'transforming principle' in Griffith's experiment.
They purified biochemicals such as proteins,$DNA$,and $RNA$ from heat-killed $S$ cells to observe which of these could transform live $R$ cells into $S$ cells.
They discovered that $DNA$ alone from $S$ bacteria caused $R$ bacteria to become transformed.
They also discovered that protein-digesting enzymes (proteases) and $RNA$-digesting enzymes $(RNases)$ did not affect transformation,indicating that the transforming substance was neither a protein nor $RNA$.
Digestion with $DNase$ inhibited the transformation,confirming that $DNA$ was the molecule responsible for the transformation.
They concluded that $DNA$ is the hereditary material,although not all biologists were convinced at that time.