2 adjectives to describe cracksman

He was one of the most accomplished cracksmen in England, and feats which seemed impossible to me would probably be the merest child's play to him.

" A week or two afterwards, I found in one of those obscure columns of "minion solid," in which the great New York papers embalm the memory of their current metropolitan crime, the following notice: "We are informed that the burglar lately killed in an attempt to rob the Historical Library has been found to be the notorious cracksman, 'Bill Young'; but that his real name was Isaac Beardsley.

2 adjectives to describe  cracksman