I think you can love a murderer in the sense that you hope they aren't a murderer anymore.
The Apostle Paul was a murderer of Christians before he was saved by God. And he become one of the greatest Christians.
Hebrews 12:29 For our God is a consuming fire.
And for the support of this Declaration, with a firm reliance on the protection of Divine Providence, we mutually pledge to each other our lives, our fortunes and our sacred honor.