Crimes committed by strangers are harder to solve than those committed by acquaintances.
For crimes committed by acquaintances, investigation can proceed by checking each person in the contact list one by one, and by comparing interpersonal relationships, but the element of surprise in crimes committed by strangers is just too great.
Becoming a police officer for a while, you soon realize that guessing a person's behavior is a very tiresome and thankless task. And for normal people, predicting criminal behavior is also very difficult.
Take the current case for example, by all logic, it should have been the victim's husband who did it.
He had the most reason to commit murder, the most reason to take away the child. But during the time frame of the victim's death, the husband had just finished his barbecue, patting his belly in deep sleep.
