In one police report, a witness claims to have seen Yust's truck near where the remains were found the same day Kara disappeared in 2007.
Those reports also say Yust and Kara were dating at the time.
Monteil said Yust was at his home for a barbeque several years ago because Yust was in a hard rock band with Monteil's son Joe.
"It kind of just blows you away," Monteil said. "You think you see that person, talked to him, spent time with him, ate food with him and then find out stuff like this happens later."
Monteil, who talked to the 41 Action News Investigators before Runions's body was positively identified, said Yust was familiar with the area where Runions's remains and the yet-to-be identified remains were found.
"He had been out here," Monteil said. "This is probably a place where he would think in his head. That's why I think well maybe it is them girls."