had been set, if there was a vehicle nearby, he still could have gone through the door and taken off---there would have been several minutes before the police would have shown up---and then they would have been busy trying to figure out what happened--they would have been busy reading the note. There really was no reason to stop off in the basement and risk anymore time in the house, if he had a place to go to, IMO....and had a quick getaway.

It was very cold that night---how far away would the perp have gone on foot?

So....if the perp was on foot--how does that change the kidnapping scenario? Particularly if he had no place to go. Perhaps the note was done as part of the fantasy----and to also create a diversion, if someone started coming down the stairs while he was still in the house.

If it was a real kidnapping attempt, once the victim was dead, he may have thought it was all over---many have thought the same thing--why wouldn't the perp?