First contact - last warning

I want to write a murder mystery that begins, like so many, with a dead body being discovered by a fella walking his dog in bushland. The twist will be that, having eliminated all other possibilities, the police ultimately come to the realisation that it must have been the dog-walker who committed the crime. They arrest him and he confesses. All I need is a net full of red herrings involving the victim's initially suspicious family and friends to plug the gap in between :-)