So bear with me for a second, and I apologize in advance if I offend anyone, but what if SD was into drugs and had undesirable "friends of the family???" He and biomom are on the outs. He needs money. He knows that JF is getting a new gaming system for Christmas. (He even mentioned this in one of the interviews and I found it so odd, because really, a grown man excited about the little boy getting a gaming system??? excited enough to mention it when the boy is missing???? It really stood out to me MOO)
Mentions the new gaming system to (now-known recently arrested) "friend" who says I can get money for that! They go over to apartment to get the gaming system, and poor little JF is there. He knows this is trouble, hence he calls mom.
Had to off JF to cover up theft from apartment.