I found a good read called CASE MANAGEMENT for Missing Children Homicide Investigation from the US Dept of Justice, and I suspect it has been quoted here before and I just don't remember it (old age, ya know):
Here is the link and what follows below are just some quotes from it that I found interesting (you may agree or you may not and that's fine):
http://www.atg.wa.gov/uploadedFiles...uction_Murder_Research/CMIIReport-Summary.pdf
The murder of an abducted child, particularly by a stranger, is a rare event. There are
estimated to be about 100 such incidents in the United States each year.
Paraphrasing, it is usually girls, 11-12 yrs old, and they meet within 1/4 mile (3 blocks) of her house.
The missing child should be reported right away and every detail told, because it usually takes the police 2 hours to start investigating and
the child is usually killed within the first 3 hours. An immediate response to a missing or abducted child may be the difference between life and death for the child.
The average killers is 27, unmarried, lives with parent or alone, unemployed or works as an unskilled laborer. Most of their victims are victims of opportunity, and sexual assault is most often the motive.
The distance from the Murder Site to the Body Recovery Site again decreases
to less than 199 feet in the vast majority of cases, so neighborhood MUST be searched thoroughly right away.
It was discovered that once the murder investigation has begun, the name of the killer is likely to be in the investigative file within the first week, so not uncommon for the police to have talked to him that first week and
the media is much more likely to have a positive effect on the investigation than a negative one.
Please read the whole document though. There were a lot of interesting statements I did not mention here.