SAN DIEGO -- The father of missing Escondido teenager Amber Dubois said Wednesday the defendant in the death of Chelsea King was on a list of registered sex offenders he reviewed after his daughter disappeared.

Maurice Dubois was at the San Diego County Courthouse for the arraignment of John Albert Gardner III, who is charged with murdering 17-year-old Chelsea.

Dubois said that while Gardner was on the list of people he reviewed, he doesn't know whether he was questioned by law enforcement.

Amber Dubois was 14 years old when she disappeared in February 2009 while walking to Escondido High School.

As in Chelsea's case, a large contingent of law enforcement officials and civilian volunteers searched for Amber. However, she remains missing more than a year later.

"My frustrations are immense," Maurice Dubois told reporters. "It's been a long, long year."

Asked whether he believed Gardner played a role in Amber's disappearance, he said he hoped not, "but in the back of our minds" the family knew that it was a possibility.

"The likelihood is much larger than we'd ever want it to be," Maurice Dubois said.

He said he has spoken with detectives from the San Diego County Sheriff's Department and Escondido police since Gardner's arrest.

He said he briefly spoke to Brent and Kelly King -- Chelsea's parents -- after her body was found Tuesday.