Mmm, sorry, can't see them finding a few bits and thinking "that'll do". Particularly as they'd not found what I'd consider key bones for proving homicide - skull and any from the torso (e.g. for indications blunt force trauma, stabbing, shooting). It's just not their job to make a decision as to how much is enough. I'm really puzzled as to why they would say they had found all they were going to - even if for some reason they thought it was true, it's not a statement I'd want to make publicly!
IMO, by them finding only a few of Dylan's bones, that it would be only the beginning of the search. To our knowledge, he started out as a healthy 13 year old boy, who's life was taken by some unknown manner. If he had died in a tragedy, like 9/11, then a single bone fragment might be the only remains that the family would be given to bury. But because he was most likely murdered by someone who probably dumped his entire body, I would have to agree that the finding of a few bones should intensify the search, not end it. Assuming that Dylan was hit in the head with blunt force trauma, then there might be multiple pieces of skull bone. Adolescence still have sutures, and blunt force trauma could cause fractures on these lines. Sutures usually become more solid (joined), after the age of 30. If he was killed with a gunshot wound, then a single piece of skull bone could show signs of internal or external beveling. Internal beveling from the entrance wound. Close range shots could show signs of gunpowder burning. Bones that have been found that have animal bite marks or breaks, that are lighter than the rest of the bone, might show a postmortem break or damage. If the bone and damage are all the same color, then that might show a perimortem injury or damage. As far as strangulation is concerned, some signs of strangulation are a broken Hyoid bone, the horseshoe bone beneath a tongue. The problem with adolescents, is that their Hyoid bones are still flexible. If Dylan was strangled, then this could have occurred, without the Hyoid bone having been broken. I would think that LE would be out there with Cadaver dogs, which have been known to find bones as old as 25 years. If they found Dylan's shoelace separate from his Air Jordons and tied in some specialized knot (like a truckers hitch), then they might be looking at suspect with a certain occupation. I am guessing that the average nylon shoestrings have at least a few hundred pounds of tensile strength. People who have specialized hiking boots, or who have Paracord 550 bootlaces have a tensile strength of 550 pounds. Some skateboarders replace their shoelaces with OldKooks Shoelaces, and they have a tensile strength of 1600 pounds. They would have to look at what the shoelace was used for, and see if the shoelace would have the strength to do that job. Wikipedia claims that:
"Estimates have been made that significant occlusion of the carotid arteries and jugular veins occurs with a pressure of around 3.4 N/cm², while the trachea demands six times more at approximately 22 N/cm².[7]"
[ame="http://en.wikipedia.org/wiki/Strangling"]Strangling - Wikipedia, the free encyclopedia[/ame]
3.4 N/cm2 converts to around 5 pounds per square inch and 22 N/cm2 converts to around 32 pounds per square inch. So strangulation could easily be done with an average shoelace, well under the tensile strength.
Here is an older article, but still interesting, on Cadaver Dogs:
http://www.independent.co.uk/news/science/the-csi-death-dogs-sniffing-out-the-truth-behind-the-crimescene-canines-835047.html
I am not an expert in any of these areas, so please do follow up research. I am only stating some observations and opinions.