Testify (verb)

1. Give evidence or bear witness to in a court of law.
2. Give or provide evidence of or bear witness to (something).

Origin:

Late middle english: from old french testifier, from latin testis "witness" + -ficare (from facere "make").

Examples:

1. He testified in court about the events of that night.
2. She testified that she saw the accident.
3. The witness testified under oath.
4. The evidence testified to the defendant's guilt.
5. The experiment testified to the validity of the theory.