eyewitness

1. Someone who sees an event and can report or testify about it. [from 16th c.]Examples: "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."