I would guess that the authorities knew a lot of Ashley's tale was FOS. But they had their man and a nice PR story for the masses to swoon over, and to cover up some of the major screwups of the entire affair. So they either looked the other way or didn't look at all - intentionally.
Agree, in so far as the LEOs knowing where he got the meth that they found in his system. They had their wonderful PR story, and after all the bumbling, they were desperately looking for an ending like this.
Say, isn't this the story about the 55 year old grandmother they put in charge of guarding this guy, that nearly tore her head off before murdering a bunch of people?
These were the same cops that, what was it, looked for a getaway car for 12 hours before finding it on the next floor down in the parking structure the guy jacked it from.