When Karen Doll-Murphy learned that convicted sex offender John Albert Gardner III was linked by police to the disappearance of Chelsea King, she got angry. Then she got busy.

The Escondido life coach and mother of two created a Facebook page called "Support One Strike Law for Sex Offenders," with the goal of lobbying legislators to pass a law that would put convicted sexual predators away forever.

Gardner, charged with murder and rape or attempted rape in the death of 17-year-old Chelsea, a Poway High School senior, served five years in prison for a 2000 attack on a 13-year-old girl in Rancho Bernardo.

Escondido police said he is also "a focus" in the investigation of the death of 14-year-old Amber Dubois, whose remains were discovered off a dirt road in Pala on March 6, more than a year after she had gone missing while walking to Escondido High School.

"This spurred from what happened to Chelsea King and now Amber," Doll-Murphy said. "This is an emotional issue. I go from fear to rage. For me, that was just the final straw. That was the tipping point. This guy should never have been out to offend again."

Doll-Murphy's group is one of several efforts on Facebook advocating changes to laws dealing with sex offenders. Those are among many other pages reflecting anger and frustration in the wake of the deaths of the two North County teenagers.

Those efforts have definitely attracted attention.

More than 6,000 members joined Doll-Murphy's group in six days, and the number is growing quickly. A group called "Chelsea's Law" has attracted 3,800 members and more than 1,000 have joined "Chelsea King Tribute ---- 1 And Done."

Doll-Murphy is trying to focus the anger of many of the site's members into positive action toward changing California laws dealing with violent sexual offenders.

She encourages them to send letters to their state Assembly members and senators demanding action on a "clear-cut one-strike law for sex offenders."

In a letter she e-mailed to Assemblyman Nathan Fletcher and state Sen. Mark Wyland, Doll-Murphy called for sentences of life without parole "and depending on the circumstances that they get the death penalty" for sex offenses.

She also urged that legislation include provisions for the insertion of microchips into all convicted sex offenders, past and present, so their whereabouts can be tracked.

Along with the letter-writing effort, Doll-Murphy is seeking people interested in starting a nonprofit to work toward changing the law. She is also rounding up martial arts instructors willing to volunteer to teach self-defense classes for children and adults at area high schools.

Doll-Murphy said she wants to create an "action-oriented group."

"Our goal is not to have a site where people go to express their feelings and become an angry mob," she said. "I remind people once a day to keep in action and on purpose, to direct their anger in a positive way to get this law passed."

Despite Doll-Murphy's admonitions, many of the comments on the site could be considered harsh.

"They should hang the bastard. Each and every one of them. Instead of sending them to prison to be released to offend again," one member wrote.

Most comments, though, are constructive and supportive. Doll-Murphy said she is amazed by the response to her appeal.

"Every day I see it (the site), I think, 'What a blessing.'" she said. "It's amazing to see it growing so quickly.

"I have this vision of people uniting and making this a nationwide movement. ... I know that it is very difficult to get anything changed, but I'm optimistic that with enough people we're going to move forward."

Contact staff writer Jeff Frank at 760-740-5419.