what does the bible say?
Saul died in battle as a direct result of his unfaithfulness, including consulting a medium (1 Chronicles 10:13–14). During a fierce battle where the Philistines had the upper hand, he was badly wounded by an archer (1 Samuel 31:3; 1 Chronicles 10:3). Because he considered is a humiliation and disgrace to be killed by the enemy, Saul asked his armor bearer to kill him (1 Samuel 31:4a; 1 Chronicles 10:4a). However, the armor bearer would not, so Saul fell on his sword, killing himself (1 Samuel 31:4b; 1 Chronicles 10:4b). So, the biblical account is that he died by suicide, and that is considered the more accurate one.
However, a young Amalekite, who apparently wanted to gain favor from David, who had been pursued for years by Saul, claimed that he killed Saul. He claimed that Saul asked him to kill him (2 Samuel 1:9), saying that he did as asked (2 Samuel 1:10a). It’s unclear whether the man specifically lied, taking credit for Saul’s suicide, or exaggerated his role from being present when Saul died. Regardless, David was not at all pleased that someone would kill whom God had anointed as king, and ordered the Amalekite be put to death (2 Samuel 1:14–16). In effect, the Amalekite hung himself by seeking glory at the expense of Saul.