。
The court sentenced him to death.
Literal
Court [topic-は] him [object-を] death-penalty [to-に] consigned-[past-した]
処する ('to deal with, sentence, impose') is a formal verb used specifically in legal contexts for imposing sentences. 死刑に処する = 'to sentence to death'. The を + に pattern marks the person (を) and the sentence/verdict (に).