eyewitness

noun

1. Someone who sees an event and can report or testify about it.

   “And the girl's fate he could picture as plainly as though he were an eyewitness to it.”

   “The evidence of eyewitnesses and the distance travelled after the initial derailment confirmed that the train was travelling at 45 to 50 m.p.h. as it became derailed.”

   “There was no eyewitness report or independent confirmation for the strike near the town of Mareesa that was also reported by the Dubai-based Al-Arabiya television network.”

verb

1. (transitive)To be present at an event or incident, and see and observe it.