1, Offender MUST know the home so well.
2, Offender MUST be stronger enough to carry 70 lbs people to go through door, even window WITHOUT making any noise...
3, Offender MUST have some accomplice to help him/her outside, or he is too "brave" even after he carry a girl and check outside himself.(Offender should be afraid of someone to look them to go outside)
4, Offender MUST know how to use anaesthetic, or how he made no noise of girl.