Even the worst pyschopathic killers in the history of criminal justice can usually dredge up friends who'll tell the jury what wonderful people the perps are (I'm sure Ted Bundy could find plenty of people to say how charming and fun to be around he could be).
This kind of testimony carries absolutely zero weight, or rather it shouldn't, except for those easily duped by courtroom tricks of glib defense attorneys. The facts of a murder trump stories of what a wonderful person a killer was.
Adolf Hitler was a wonderful painter, and he loved dogs.
If you take that as a rule, then everything presented as evidence in court is suspect from the get-go - you can’t believe anything at all that any sworn witness says because anyone can lie.