Usually none of it is planned, that's where it gets interesting with child abduction murders
Years ago when I was a paramedic, i worked at a large metropolitan children's hospital, the first thing we were taught and any pediatric nurse or doctor will tell you this, "Kids aren't just small adults they are completely different".
The same thing applies to those who prey on kids, even in offenders who switch from adults or children or vice versa, their MO doesn't usually change that much depending on the victim preference. Therefore you cant really compare child killers, to adult killers, even in cases, where they have killed both the psychological signature will be consistent throughout their crimes .
Israel Keys was a bit of an enigma, but he was also more of an impulsive sociopath, like most sociopaths, he dabbled in all types of crime, he took a great deal of care not to be detected, but in the end he was caught.
In sexual child murders where the victim is abducted,
The Offender, is usually there in the area because he lives or works nearby, IE they belong there , in some cases, its a route they take regularly etc..
They are most often sexual deviants, with a record, who come upon their victims by chance, most victims are usually on their way to or on their way home from school.
The sole factor they tend to pick a victim is because there is no adult present, the presence of another child wont usually deter them, as a matter of fact the second child may become a victim themselves. As we've sen here and in Delphi.
Now that doesn't mean there aren't offenders out there looking for a victim, there are , and some may actually set out to go abduct a victim, but that type is extremely rare, and almost always already serial offender, as in the case of Duncan (now dying of brain cancer thankfully)
In most cases, they aren't usually out on the hunt actively for victims, they are basically rapists/killers in waiting if you will, and if their planets align, they grab the victim.
For this individual to approach 2 kids in broad daylight , and abduct them both tells me hes not really concerned about being seen, probably because its not uncommon he is .
Often pathetic oddballs, they don't have a large friends circle, and usually live with their parents. Some may be married but its not usually withing the normal parameters of a "healthy " union if you will.
I explain it to my students like this, this isn't an active predator , its an ambush predator, Its not like a lion on the prowl for prey, but more like a Crocodile waiting for something unsuspecting.
The motive for their crimes is almost purely sexual, and unlike adult abduction killers, they usually don't have something that set them off prior to.
They are usually between 27-36 years of age, it'll change if they were in custody for a time, most have been at some point.
The victim is usually killed within 1-2 hours after they are abducted, which brings up a heart wrenching point , in most of these cases, the family isn't aware the child is even missing for usually 2-4 hours after they have been abducted... So in most cases, unless an abduction was witnessed, the child is already dead before they are even reported missing.
The murder usually takes place very close to where they are found, and the offender is usually very familiar with the body recovery site .
One factor about these guys, is they revisit, something like 85% of them revisit the bodies, and i feel confident saying that up UNTIL they were discovered, he went back to their bodies. SO ANYONE that was ever spotted in that area between the time they went missing to when they were found should be interviewed.