Not that it is particularly likely, but do we really know that it was Claudia in her home that night, or could it have been somebody else staying there?
Possibly there with her, or even waiting there for Claudia to return home, either with her approval, or not.
speculation, imo.
I've often thought someone might have stayed with her that night, but I would think they tested items in her house - bed sheets, towels, mugs etc - for signs of A N Other person. If they found anything I think by now they'd have said "we know someone slept there".
Actually, hang on, they HAVE said they know people were in the house who haven't come forward, but not necessarily over night or that particular night. They will have tested everyone they've arrested plus probably others from the Nags etc, so who else's DNA was found that they haven't connected yet?
Did a complete stranger did snatch her off the street?
Did someone she knows offer her a lift?
Did someone stay over and drive her to work?
Did something happen overnight?
I think, given the "arguing couple" scenario, it seems most likely that there was a love interest, whether he stayed the night or not I think it could well have been them arguing and she got into the car that morning. How busy is that road at 6am? Could he have bundled her into a car without anyone passing by?
Occams Razor and all that, makes sense there is someone who's presence in the house has been proven yet he has not come forward. He did it.