I'm not sure if it's a true story as there could be many fictional or exaggerated accounts with such a title. It might be a very disturbing and tragic claim if it were true, but without proper sources, it's hard to verify.
The killer should face life imprisonment. Taking someone's life, especially a close friend, is an unforgivable act and they should be removed from society to ensure public safety.
It could be a case of self - defense gone wrong. Perhaps the person felt threatened by their BFF in some way, but in the moment of trying to protect themselves, they ended up taking it too far.
The motive could be jealousy. Maybe there was something the killer wanted that the BFF had, like a relationship or a job opportunity. It's a tragic situation.
Some people might turn to religion or spirituality. They may believe in the concept of atonement or redemption. By praying, doing penance, or following religious teachings, they hope to find some peace within themselves.
Jealousy could be a possible factor. Maybe there was envy over the preacher's daughter's seemingly perfect life or the attention she received. Or perhaps there was a conflict over a boy or some other personal matter that got out of hand.
It might have been an accident. For example, if they were involved in some dangerous activity together like handling a weapon or driving recklessly, and things went horribly wrong. Maybe during a hunting trip, a misfire of a gun accidentally hit the bff.