Sentence:  `` This was a man of incredible criminality , of a criminality effectively without limits ; a man apparently foreign to the very experience of love , without mercy or pity ; a man in whose entourage none was ever safe ; a man whose hand was set against all that could not be useful to him at the moment ; a man who was most dangerous of all to those who <WSD>were</WSD> his closest collaborators in crime '' . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)