Yes, that's the only reason why he would be strip searched, to look for marks and scratches. So was this done after Celina was found or before?
Maybe her body had broken fingernails on it but maybe the water washed away what skin might have been under there. But broken fingernails on a victim is a strong sign those nails were dug into somebody. Did WN get a full body search, too? Sounds like his wife blames him for doing this and she might well be right.