If she was taken by car then she really could be anywhere. However if they are pretty sure they know the car, and they also know the car was back home lets say 25-30 minutes later, then they may be putting 2 and 2 together to identify the park as a private spot for a crime to be committed that still fits that timeline.
So it's not a clue in the park that has them searching there. It's that they are sure she goes in, but unsure if/how she came out?
So if she was taken out of the park in car, they are currently looking in the park for some clue towards that?
Does that mean that they are at this stage not sure what they are looking for in the park, only that they are looking for
something/anything in connection with Libby, PR, AN Other, or anything linked to that night?
Put it another way with a different example: The Police have Suspect A, and they believe what they need to nail Suspect A is on a SIM CARD in his possession. IF they are certain that sim card is in his house they will keep going until they find it. They will empty the entire contents of the house into a secure warehouse and finger tip search every item. The will take the carpets out, they will take back wall paper, remove fixtures/fittings. Time and manpower is not an issue IF THEY BELIEVE that Sim card is in that house they KNOW they will find it.
Did you notice that when they were searching PR's house, they were looking at the loft FROM THE OUTSIDE with an infrared camera. They absolutely would have been all over the inside of that loft, probably also with infrared.
So for instance, even a park as big as Oak Road Playing Fields/Beresford Park IF the Police WERE CERTAIN that a weapon had been discarded in the park, they would be certain they would be able to find it. They would finger tip search, time and manpower no issue, until they found it.
I also believe they would be briefing the media "We are lookign for X in this park, we are sure it is there and we WILL find it".
They've never made any such statement in this case. If they were looking for an implement, or traces of a car in a case they normally would say. Again, even if they didn't state they were looking for a body, I have not seen any evidence of dogs in the park. I've seen endless photos of marine units, people clearing undergroath and looking through bins, but ne'er a sign of a dog.
Which leads me to believe that they don't know what they are looking for. Which makes it an open ended search, there literally could be NOTHING in that Park of any relation to this.