Wallflower — William Bayer

Not since the infamous "Switch" case had Detective Janek seen such perverse brutality. The killer hod defiled the victims' bodies so carefully, so lovingly, that only a mind twisted by the most extreme sexual obsession could conceive such acts. But now Detective Janek must enter this bizarre state of mind. He must think like a killer to capture a killer. Worse yet, he must open the pages of his own murdered goddaughter's diary--and enter a secret world of lurid passion....

This time it's personal. This time Janek's out for blood.