Personal grudges could play a part as well. For instance, if the yoga teacher had a relationship with someone and then ended it, the scorned person might have become the 'killer' out of anger and a sense of betrayal.
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.
The 'yoga teacher killer' real story could involve many aspects. It might be a case where the perpetrator had a particular motive related to the yoga teacher's personal life, such as jealousy over relationships, financial disputes, or some form of revenge. Maybe the yoga teacher had some secrets or was involved in something that led to their death. Without more specific information, it's hard to tell the exact story.
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.
One possible motive could be greed. If there was something valuable among the friends, like money or property, a friend might kill to get it.
As I don't know the real story of this Kasauli serial killer, it's hard to say the motives. But generally, motives for serial killers can include things like power, control, or psychological issues.
The teacher might have had a deluded idea of 'helping' the student in a very wrong way. They could have thought that by abducting the student, they could 'protect' the student from something they perceived as harmful, like a bad home environment. However, this is still completely unacceptable behavior. Another aspect could be that the teacher was simply a criminal minded person who saw an opportunity and took advantage of the trust the student had in them.
Financial gain could also be a motive. For instance, if there was an inheritance or some sort of valuable asset at stake, and someone wanted to eliminate the competition, they could use the 'killer soup'. Another motive might be jealousy. Maybe someone was jealous of another person's relationship or success, and decided to use the soup as a way to harm them.
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.
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.