And he said unto me, Who art thou? And I answered him, I am an Amalekite.
The man who answers the question about who he is is the messenger who arrived claiming to have put Saul to death, and in his answer he declares himself to be an Amalekite. The exchange records his own identification, fixing his nationality and his connection to the report of Saul's death. That self-given testimony became the evidence that condemned him, for by his own mouth he admitted the act. On that ground David treated him as guilty and executed judgment upon him for striking down the Lord's anointed.
The man who answers the question about who he is is the messenger who arrived claiming to have put Saul to death, and in his answer he declares himself to be an Amalekite. The exchange records his own identification, fixing his nationality and his connection to the report of Saul's death. That self-given testimony became the evidence that condemned him, for by his own mouth he admitted the act. On that ground David treated him as guilty and executed judgment upon him for striking down the Lord's anointed.