Evidently in the new canon, this has been disavowed, but I've really liked the theory that it was Boba Fett that Vader had hired to secretly look for the droids in Tattooine, & it was him that killed Owen & Beru.
The story went that Vader was secretly always looking for any advantage in his pocket for when he eventually went up against Palpatine. He'd heard the Death Star had some flaw, & Vader wanted to know what it was, so he hired Fett to hunt them for him on the down low. Since he was already there in Jabba's palace, it wasn't too hard to do.
He tracked them to the Jawas, killed them, tracked them to the Lars homestead, killed them, then went to Mos Eisley since that'd be their best bet on leaving the planet. When Jabba came to town to confront Solo, Fett hooked back up with him to provide back up in case Chewie got out of hand.
When Vader heard about the death toll Fett had left in his wake, he felt it drew too much attention to basically a Black Op that Vader was running behind Palpatine's back. Plus, he didn't know if Luke would be with the Falcon crew when Fett caught up with them, so he gave the "No disintegration" order.
I've always loved that theory, but alas, it wasn't to be.
The story went that Vader was secretly always looking for any advantage in his pocket for when he eventually went up against Palpatine. He'd heard the Death Star had some flaw, & Vader wanted to know what it was, so he hired Fett to hunt them for him on the down low. Since he was already there in Jabba's palace, it wasn't too hard to do.
He tracked them to the Jawas, killed them, tracked them to the Lars homestead, killed them, then went to Mos Eisley since that'd be their best bet on leaving the planet. When Jabba came to town to confront Solo, Fett hooked back up with him to provide back up in case Chewie got out of hand.
When Vader heard about the death toll Fett had left in his wake, he felt it drew too much attention to basically a Black Op that Vader was running behind Palpatine's back. Plus, he didn't know if Luke would be with the Falcon crew when Fett caught up with them, so he gave the "No disintegration" order.
I've always loved that theory, but alas, it wasn't to be.