That is how they do it. They have a starting point and thoroughly comb each inch. I've done this before, this is the correct way to do a search. At the beginning of the park, there could be a cigarette butt tossed belonging to suspect or in some cases, victims, if they smoke, candy wrappers, gum, coffee cups with lipstick (same with butts), piece of a child's toy or small toy, even a food wrapper that might have flown out of a vehicle purchased earlier that day, pieces of clothing or sock, you get the jist.
Everything and anything they find to which they deem is relevant to the case is properly picked up by gloved hands and bagged for evidence.
A public search that involves LE teaches you to not touch a thing, the officer comes over, looks at it, and bags it or passes up, knowing it's not important.
A public search with LE is from either arms length, if there is enough people, to 8-10 feet apart. When something is found, the person yells "stop", and a chain reaction of "stop" is heard from left to right, while everyone stands still, silent, until LE gives the signal to move on again. Everyone must got straight ahead and never deviate from that, for the safety of the searchers.
I don't know if this helps anyone or not, but just figured I might be able to help those who may have not done searches in the past.
