. >> detective howard cole said investigators had to take a close look at reid. >> any time you haveuation of this nature, nine times out of ten it's inner circle, it's spouse, it's a business associate, a friend. >> remember when reid first went to the sheriff's office on the day quinn was kidnapped? >> did you go anywhere today where you would have to go outside in any fashion? >> detectives immediately thought something was suspicious. >> do you know how you got blood or mud on your shoes there? >> there's nothing on my shoes. >> it tells us we don't rule anything out. >> and during that interview, investigators learn that quinn and reid had endured some major problems in their relationship. >> what did reid gray tell you about his marriage? >> their marriage, for lack of a better way of putting it, was rocky. >> there's an ugly side of our marriage. she went out and didn't come home. she was pretty intoxicated, i looked in her purse and saw underwear in her purse. i'm like, quinn, it's time to be honest. >> he did explain a lot of circumstances surrounding past infidelities both