Why can't the cops figure out who buried my wife in the front yard?

I used to live in the suburbs in the bay area. Everyone could see my lawn in the neighborhood. Someone killed my wife and buried her in my front yard on a Sunday when I was at church asking the good lord for forgiveness. I had been digging a large hole in my yard for a garden. The neighbors said they saw a guy dressed for church shoot my wife and bury her in the front yard during the afternoon.