WHO KILLED SAUL?

I Samuel 31:4 Then said Saul unto his armourbearer, Draw thy sword, and thrust me through therewith; lest these uncircumcised come and thrust me through, and abuse me. But his armourbearer would not; for he was sore afraid. Therefore Saul took a sword, and fell upon it. (KJV) II Samuel 1:10 (an Amalekite speaking) So I stood upon him, and slew him, because I was sure that he could not live after that he was fallen: and I took the crown that was upon his head, and the bracelet that was on his arm, and have brought them hither unto my lord. (KJV) II Samuel 21:12 And David went and took the bones of Saul and the bones of Jonathan his son from the men of Jabesh-gilead, which had stolen them from the street of Bethshan, where the Philistines had hanged them, when the Philistines had slain Saul in Gilboa: (KJV)

Saul committed suicide, as recorded in 1 Samuel 31:4. The Amalekite in 2 Samuel 1:10 was lying in his story, trying to justify is robbery of Saul's dead body (and falsely believing David would be pleased). As for 2 Samuel 21:12, the Hebrew word used there is "nakah" which can mean either to kill or to defeat, and clearly means 'to defeat' in this context.  Keep in mind that the author of all three passages is the same person, thus he would not be unfamiliar with how Saul died.  Not a contradiction.