TESTIFY

[verb] - to speak seriously about something, esp. in a court of law; to give or provide evidenceShe testified for/on behalf of her family. [I]They testified for the prosecution. [I]No one expected him to testify against his former employer. [I]He testified to having seen the man leaving the building around the time of the murder. [I]He testified that he had seen the man leaving the building around the time of the murder. [+ that clause](formal) The open door testified to (= showed or proved) the fact that she had left in a hurry. [I](formal) The open door testified (= showed or proved) that she had left in a hurry. [+ that clause]