There's more to this story....
Thank you for putting a context to all of this. A key sentence that I noticed was this, "The soap punishment rose to the level of a crime
(emphasis mine) because of the malicious torture involved and the protection and help the mother failed to provide to her child."
Using soap as a deterrent is no more a crime than other forms of correction applied judiciously in the context of a loving and caring home. That was clearly not the case in the situation reported here. And yes, those adults need to dealt with as severely as the law allows.
However, cases like this should not create an attitude of fear in good parents who wisely use various methods in raising their children that are condemned by do-gooders who have the theory, but no experience.