corroborator:
(plural: ‘corroborators‘; ‘c’ is said with a ‘k’ sound)
a person who supports and strengthens another person’s opinion, belief, idea, etc. by supplying fresh information or proof,

a corroborator (M) giving supporting evidence to the investigators
When Daniel said he was not in the office when the money was stolen, the police officer asked him whether he had at least one corroborator to support his statement.
It is also evident that a corroborator who corroborates with someone has, in most cases, some personal intimacy or some sort of business dealing.
In the case of Noel Vs. Joel, Noel came up with the allegation that Joel made him supply drugs to Joel’s clients, but Joel said he did not know any of them and brought in several corroborators, ‘his alleged clients’, who confirmed that they did not know Joel but dealt with only Noel who used to sell them drugs, and with the support of those corroborators Joel won the case.
