It's almost unthinkable.  What in the sam hell was going through this creep's head when he decided to do such an unspeakable thing?  I always wonder that every time I read about an adult who kills a child.  MONSTERS. 

Hey, is he out on bail yet?  He will be, I guarantee it in this current irresponsible administration.  Humans now just have no regard for other humans, thanks to ol' dumbass joe's weirdo policies.  Life means nothing, people have lost hope, I guess.  That's the only explanation I can think of and it's not a good one.

https://www.westernjournal.com/fedex-driver-accused-murdering-7-year-old-forgiven-last-person-expect-pray-family/

The grampa will find no real comfort in "forgiving" this person, sorry man.  It just doesn't work that way.