You definatly picked it up too soon. As soon as I seen that dark blood I would back right out knowing that its a liver hit. The weather makes for a tough scenario, if you wait, you know the deer is dead, but rain will wash the trail out. BUT if you carry on you might push the deer causing it to plug up the wound, go on to neighboring property, etc. I would just wait it out then do a good grid search then check the thickets and near water. The harder you try the better your chances are at finding him, dont loose hope, but dont get too confident either.