I know this won't be the last time this has to be said but it would be nearly impossible to convict BL for theft of the van. Prosecutors would have the burden of proving beyond a reasonable doubt that (a) BL did not have permission to have the van AND (b) that, even if he didn't actually have permission, he didn't mistakenly believe that he had permission AND (c) that he intended to permanently deprive GP or her estate of possession of the van. Given the facts that we know, that would be extremely difficult to prove. More to the point no prosecutor in their right mind is going to pollute a potential capital murder case that, in all likelihood, will be based on circumstantial evidence, by also taking the time and burning credibility capital with the jury to convince them of a much shakier case of auto theft that at best may tack on a few months prison time and a monetary penalty.None of that matters. Legally, he stole her van and her belongings.
So even though it may be offensive that BL drove her van home after killing her, that doesn't "legally" appear to constitute auto theft and the bigger picture of his killing her, if he did, makes talking about theft of the van pointless and almost offensive in itself.