Depends on what you mean. I'm sure they know a lot of little details about timeline and such, but I doubt they have a clue as far as evidence against Dale. If they did he would have been arrested by now. As I said before I think they jumped the gun. They announced him as THE prime suspect and I think they were pretty confident that they would find something at Dale's dad's home and it back fired on them. Usually, but not always when someone is murdered and transported in a car there is somekind of trace evidence left behind. Correct me if I'm wrong, but they searched Dale's home and car, Dale's dads home and the Hummer and as far as we know they have not found anything. Just MO but if they would have found even a trace of blood or anything in Dale's car or homes then I would suspect he would have been arrested by now.
I am not going to pretend that I know the exact timeline and to be honest at this point I don't have an opinion as to whether I think Dale did this for 2 reasons. 1 there is no evidence as far as we know and 2 there are a lot of guys out there like Dale with a bad history of violence that have not killed they ex girl friends and sad thing is when one of them does go missing they will be the first to be looked at innocent or guilty. If Dale did murder her then he was pretty smart and by that I mean he has been able to get rid of a body with as far as we know, with no one seeing him and leaving nothing behind for the police to go on.
BBM
Someone correct me if I am wrong but I believe that Dale was named the prime suspect AFTER the raid on his dad's home, not before.