this sounds very much like reactive attachment disorder, i am pretty convinced here. Pls check the site attachmentdisordermaryland.com-great saurce for info. Also read the book by Daniel Hughes and Nancy Thomas, there others, but these guys are the best. Also, you must find an attachment therapist, a regular shrink will not help, you are quite correct observing that regular behavioral techniques do not work here, such kids do not care, they simply do not have conscious - that is why they feel no remorse.