Well, apparently they don't want to release any record from 1992 - I guess it was claimed because of the ongoing case. Someday we might get the whole scoop on whether they really did anything in 1992 besides show up at the gas station, leave because no one was there, and at some point report it to El Dorado County.
There's a whole bunch of stuff they could have done, but I'm gathering that they did not request the public be on the lookout when someone gave this tip - like put it in the newspapers or on posters (esp in close proximity to Jaycee's Missing posters) that they are looking for this big old honkin', very Yellow, boxy Dodge van.
I suggested elsewhere that could they could also have alerted LE to look for it and ask any police helicopter searches keep it in mind or even make a couple of extended passes over the area - I guess Garrido could have immediately put it in storage or covered it, but why do I think he didn't even bother?
I think Garrido didn't show up in the SO database till later? 1999? or am I way off - my mind is a little mushy tonight. But still, he was on Parole wasn't he?