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.
Since we don't have the details of the Kasauli serial killer's story, it's only speculation. Some serial killers are motivated by a desire to exert power over their victims, others might have had a traumatic childhood that led to a distorted view of human life. There could also be cases where the killer is mentally ill and their actions are a result of their illness.
Not having knowledge of the specific Kasauli serial killer case, we can only look at common motives among serial killers. Revenge against a certain type of person or group, sexual gratification in some cases, or just a compulsion to kill due to a deeply rooted psychological disorder. Without the real story, these are just broad possibilities.
Since I'm not familiar with a particular 'Kasauli serial killer', it could be a case that is not widely publicized globally. It might be a regional mystery. Maybe checking local archives, interviewing long - time residents of Kasauli, or looking into regional crime databases could help uncover the real story.
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 insanity. Maybe he just has a deranged mind and the act of killing gives him some sort of twisted pleasure. The muffins could be a part of his delusion, like he believes his victims are ingredients for some special muffin in his warped mind.
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.
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.
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.
One possible motive could be a desire for control. Serial killers often feel powerless in some aspects of their lives, and killing gives them a sense of power over others.
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.