San Francisco officers investigating the 1984 disappearance of then 10-year-old Kevin Collins visited his family in Contra Costa County Tuesday night to discuss new developments in the case.

Police left the apartment of Ann Collins in Concord at about 7:30 p.m. KTVU got exclusive video of the three investigators departing after they spent several hours talking with her, two of his sisters and a brother.

Police showed the family a photo of lead suspect Dan Therrien, a San Francisco resident at the time of the kidnapping who died at the age of 51 in 2008.            

They also showed the family photos of what he looked like in 1984 when two witnesses say they saw Kevin talking with a man with a big black dog.

Cold-case investigator and retired homicide inspector Joe Toomey told KTVU Tuesday that Therrien fit that description. He had a black dog back then and was interviewed by police just five days after Kevin disappeared.

"I'm convinced the investigation is going in the right direction," said Toomey.

That direction led them last week to dig up the concrete floor of the garage of the house on Masonic where Therrion lived when Kevin disappeared.

Police said two different cadaver dogs hit on the same spot. KTVU learned the bones are all small fragments, only a few inches long. The coroner said he believes the fragments may be dog bones and not human.

The bones are now in a lab for analysis.

Sources told KTVU that the two witnesses who saw Kevin with a man with a dog back then could not pick Therrien out of a photo lineup in 1984. Toomey confirmed that fact.

"That's correct. Both could not," said Toomey.

When asked if authorities were looking for the car therrien drove back then, Toomey answered "We're not seeking a particular vehicle at this moment."

However, when asked if police already had a vehicle, he would not comment.

When Ann Collins left her apartment with her daughters, she said police asked them not to talk with the media until after a news conference scheduled for Wednesday.