>> we have basically 1250 acres of trash. that becomes a crime scene. >> but investigators got a huge break when they learned landfill officials were far better organized than they thought. >> one of the things that i was quite amazed by was how strategically placed or lined out the trash is that is put in grids. they can actually go back and determine a region or area where trash was dumped from a particular area of the city. >> so volunteers searched the area where trash from joanna's neighborhood was dumped. but even then, it was almost will two years worth of trash almost a quarter of a million tons of it, to dig through. hundreds of volunteers participated in the search. >> to us, it was a phenomenal effort that they were willing to do for our daughter. >> after 12 weeks, investigators had to consider the possibility