corroborate

Corroborating evidence (in "corroboration") is evidence that tends to support a proposition that is already supported by some initial evidence, therefore confirming the proposition. For example, W, a witness, testifies that she saw X drive his automobile into a green car. Meanwhile Y, another witness, testifies that when he examined X's car, later that day, he noticed green paint on its fender. There can also be corroborating evidence related to a certain source, such as what makes an author think a certain way due to the evidence that was supplied by witnesses or objects.