Another motive could be coercion. Maybe she was part of a gang or some sort of criminal group that forced her to kill. They could have threatened her or her family if she didn't comply. Or perhaps she was in a situation where she thought killing was the only way to protect someone she cared about. For example, if she was in a war - torn area or a place full of violence, and she believed that by killing a particular person, she could save her friends or family from harm.
One possible motive could be revenge. If she has been wronged or bullied severely, she might feel that killing is the only way to get back at those who have hurt her.
Self - interest is another motive. Like Susan Smith, who was having an affair and saw her children as an obstacle to her new relationship. She was so focused on her own desires that she committed the unthinkable act of killing her own children for her own self - serving reasons.
Mental health issues might be a factor. A 16 - year - old with undiagnosed depression or anger management problems could be more likely to commit violent acts. Also, being influenced by violent media or a bad group of friends can play a role.
One possible motive could be money. Maybe she was after an inheritance and decided to eliminate those who stood in her way.
Well, revenge might be a motive. Maybe Ruth Finley did something in the past, unknowingly or not, that offended or hurt someone deeply. And that person, nursing a grudge, decides to take revenge by becoming a killer in the story. Another possible motive could be power. If Ruth Finley stands in the way of someone's quest for power, whether it's in a social, business or other context, that person might be driven to kill her to remove the obstacle.
Jealousy might be a motive. For instance, if she felt that another family member was getting more attention or love, she could have lashed out. Another aspect could be mental illness. If she had an undiagnosed or untreated mental disorder, it could have led to violent behavior.
One possible motive could be attention - seeking. The person behind the fake story might want people to focus on them or the 9 - year - old in a dramatic way.
One possible motive could be jealousy. Maybe there was some sort of envy between the parties involved that escalated to this tragic outcome.
I'm not sure which specific 15 - year - old killer girl story you are referring to. There could be many fictional or real - life accounts that might fit this description. Maybe it's from a particular book, movie or a real - world crime case that has been sensationalized.
It could also be related to some past secrets or grudges. Perhaps there was an incident in the past that the friends had forgotten about, but the killer held onto it and let it fester until it led to murder. Say, a childhood incident where the killer felt wronged by the group of friends but never spoke up about it.