Ok, so assuming this is the case, IMO SP would have had to do something horrible to them for the perps to abduct her and torture her for three weeks. While I can see why you think they knew her, I don't see SP as being someone who would make these perps so mad that they'd do that to her. She wasn't involved in LE or any other objectionable dealings that we know of. She wasn't a high profile person. She was a typical stay at home mom. I think she was taken for ST and released because she turned out to be useless due to all of the media attention her disappearance garnered. Besides, the VI seems to think this crime points to ST if I'm not mistaken.
If the abduction motive was revenge or maybe being in business with some bad people it doesn't necessarily mean SP was involved. Somebody close to her could have been the one who had trouble with the abductors. Perhaps SP was taken because she was an easier target.
Abducting the person who you are trying to extort money from doesn't work because it's hard to get money together when your locked in a basement. Taking a young mother and beating and branding her would be a very effective way to make somebody give you what you want.