There are two tribes on an island: truth-tellers and liars. The truth-tellers speak only the truth while liars speak only lies.
A traveller came across three natives of the island and asked the first native whether he was a truth-teller or a liar. The native replied in a voice so low that the traveller could not hear his the answer.
So he asked the second native: “What did he say?” to which the second native replied: “He said he was a truth-teller”. At this point the third native, without being asked, stated that the second native lied.
Was the third native a truth-teller or a liar? Provide a convincing argument to support your claim.