Interesting points from both previous Correspondenents.
In most cases, books are written from the point of view of scientific or ciminalogy perspectives, rather than any attempt to glorify the crimes, or criminals that commit them.
I would dispute that authors are benefiting from the misfortune of the victims - that accusation could be leveled in a vast number of circumstances.
For instance, are news journalists reporting on natural disasters benefiting by being paid to observe and comment on such events?
Are airlines benefitting, albeit indirectly, by flying aid to famine victims?
The list goes on.
I think you have to take a detatached perspective and view these books as theyr are intended - an attempt to analyse and explain, rather than entertain, although that must, by the nature of free speech be an unavoidable by-product.