cover his tracks. so do you go to the prosecutor at that point and say, we got it, let's go to the grand jury, let's get an indictment? >> yes. >> and he said? >> he said, you're close, but you're not there. need a little bit more. >> what's he need? >> he needs something placing nelson, an eyewitness, physical evidence, something placing nelson back in the area on the day of the homicide. >> do you think you were ever going to get more than you had? >> yeah. we knew this was the beginning. there's more out there we have to keep digging. >> digging. it's in the detective's dna. and now the erie murders would find him digging through a box of moldy, old receipts. like little jack horner, tommy ray pulled out a plum. when we return the detective's discovery. would it help him catch the killer? >> divine intervention plays a big part in here. >> but just when he thought the case was solved, his suspect slipped away again, when "unfinished business" continues.