Well, I'm not prepared to offer a specific theory with names, but I'll make some observations about what one might look like.
First, anyone who has experience with clandestine operations, like running an agent in the field or an informant in the middle of a criminal conspiracy, will be able to tell any number of stories just like those you mentioned. The agent runner may be skilled in the dark arts, but the agents are very often doofuses. As a general rule, strong, competent, self-assured individuals don't get easily manipulated into betraying their country or their friends. So the fact that those "on the point" are clumsy is not evidence that they are free from manipulation.
Second, what was the higher purpose? My guess is a it was a million bucks to spend on some organizational purpose.
So (still guessing) imagine that a clandestine or semi-clandestine organization somehow ran across a pack of easily manipulated doofuses and whackos (Chad, Lori and Alex, plus hangers-on) who had close access to an attractive target (poor, tragic Charles). And (still guessing) this organization planned a nice clean assassination attempt in January, it misfired, and (as can happen when running a pack of doofuses) the op began to run out of control. But the objective remained, at least through October. Assuming (still guessing) that the organization is seriously scary, the pack was frightened into trying again and succeeded in a sloppy and unprofitable assassination in July. Still scared, the pack tries again with Brandon in October, and fails again. By late October they've murdered the children in an attempt at self-preservation and Tammy to raise money, but all that generated way too much risk of discovery (final guess) for the organization and they pulled out, leaving us where we are, which is with what looks like an isolated group with too many loose ends.
