The taint of the murder

2 Samuel 3:22-39
Joab murdered Abner. David said to his men, "Do you not realized that a price and a great man has fallen in Israel this day? And today, though I am the anointed king, I am weak, and these sons of Zeruiah are too strong for me. May the Lord repay the evildoer according to his evil deeds!"
David leads the nation's mourning for Abner. Despite a public declaration of innocence, the taint污點 of the murder remains with him all his life.
Why?
Abner's death is to David's advantage, just as the death of Ishbosheth will be; both weaken the support for Saul's family.
No matter what it was, to be king have to do the public declaration of innocence to this event. And somehow it is uneasy to erase the taint in memory of people.
How?
Taints of the evil are remain with us in our life when we did it. The Lord knows the heart of each one.