There's definitely something really strange with this entire case.
First Ricci was known to the family. They likely thought they were helping out someone who was down on his luck, and both parties were benefitting. Ricci was probably working for less than market wages, because he couldn't get a proper job where they checked references.
Ricci may have been attempting a kidnapping, but the ransom demand was foiled when it became apparent that MK was in the room and had heard his voice.
The ONE thing I can't get over is the mean-spirited blame it on the victim's family mentality that seems to prevail in these threads. Perhaps the poster who said that these vicious theories stem from a desperate need to convince oneself that "it couldn't happen to me," is right.
Now, questions...
If there were more than one or two people involved here, that shoots down the "burglary gone wrong" theory, IMO. The Smarts are obviously well-to-do, but if their last name isn't Rockefeller or Vanderbilt, why target Elizabeth specifically? Surely there are wealthier families in the area. Unless...1) those involved were -sure- they could get money from the Smarts, for reasons entirely unrelated to Elizabeth. Which goes back to blackmail of Mr. Smart (not likely, IMO, but not ruled out, either), or 2) those involved picked Elizabeth because they thought she would be an easier target, based on the fact that maybe they already had a way into the home, and were already known to the children.