This is one of the simplest explanations and an obviously possible angle of who the perp could be that I've seen presented. It would explain why guitar guy :guitar: thinks he recognizes the voice. (He said he'd recognize the voice but it could be that he recognized the voice.) It would also explain why the guy, if he showed up hours earlier when the silver van was noted, would speak to Jessica the way guitar guy reported to LE he did. He would be familiar with Jessica, the gas station, the jobs at hand, the rules, etc. So, 'hey, what are you doing out here?' fits.
Then, after speaking to Jessica, he leaves but cannot stop thinking about her. He knows there aren't any cameras, he knows what time the station closes, he knows what she'd likely be doing and when, and he knows he would like to have her but she (maybe in the past) rejected him. Maybe he begins to drink or takes some drugs and returns to the station at 10:55 p.m. and tells Jessica a lie concerning the gas station to lure her outside and then he overtakes her and gets her into the van.
Since LE doesn't tell us everything, the possibility of a previous employee being the perp seems logical and fits with some of the weird witness accounts we've heard. Also explains why LE may be taking the witness accounts very seriously. The only thing is, wouldn't LE be able to locate a particular person such as this one easily. I would think so and, by now, might have a good idea of whether or not this person is involved. Yet they haven't let on that they've made contact with sketch guy or interviewed him. So does that mean LE can't find him? Or have they found him but haven't pinned enough evidence down yet in order to arrest him.
:Welcome1: to Websleuths happy2bgrandma47.