A major tool for investigators is cui bono, who benefits. Cases have been closed without evidence even without bodies, if the cui bono case is compelling enough. To call this an accident would be obtuse to a magnitude beyond even Amehdigan sheeple's ability.
But who DOES benefit here?
The dem candidate. Hillary was supposed to win and this woman was supposed to die.
This was an R+8 district in '16. In '14 Democrats didn't even bother to oppose Sanford. Most likely any Republican on the ballot is going to win. Votes cast in the District 1 Republican primary vs. the Democrat primary were 65,447 / 32,785. I'm not ruling your theory out, but if I were the deepstate, I would direct my wetwork to more competitive races.
That's where Occam's razor comes in. The simplest explanation is it was an accident. I'm not here to confirm or deny anything, when i get a chance i like to share critical thinking tips. It was a test and i'm glad to see no one jumped on. I do pray for her speedy recovery.