ESCONDIDO, Calif. -- The man suspected of in the death of Chelsea King was being watched more than a year ago by the family of missing teenager Amber Dubois.

On Tuesday, 10News spoke with Amber's mother, Carrie McGonigle. She said her family asked investigators with the Escondido Police Department to check out 174 registered sex offenders living within the area of Escondido High School where Amber, who was 14 years old at the time, was last seen February 13, 2009.

McGonigle said she was angry when she heard about John Gardner's arrest, "'Cause I asked numerous times for Escondido PD to check out every single one."

Family friend Linda Walkup said Chelsea King could have been saved if investigators checked in on people like Gardner.

"Had he been looked at from the beginning maybe, possibly, we could have stopped what's going on with Chelsea right now," said Walkup.

Instead, Amber's family and friends began their own investigation. They located the homes of 147 known registered sex offenders in Escondido, San Marcos, Poway and Rancho Bernardo. They drove by their homes and even staked out some of those homes. One of the stakeouts was almost a year ago, outside an Escondido apartment belonging to Gardner at the time.

Family friend Vinnie Spucces showed 10News reporter Joe Little the notes they'd taken on March 28, 2009, about Gardner. They couldn't believe it when he was arrested.

"My wife dropped to the ground and says, ‘We were there. We got his picture,'" said Spucces, "We were shocked."

The family told 10News they were holding out hope that Chelsea and Amber would be found together, alive.

Spucces told 10News by phone Tuesday's discovery of what appears to be Chelsea's body is a blow to the King family and their own search for Amber.