SAN DIEGO, Calif. (CBS 8) - A registered sex offender murders a young woman and dumps her body in a remote area. We're not talking about Chelsea King or Amber Dubois. We're talking about the murder of Brittany Hart in 2007. Now the Hart family is joining a call to action.

"Here it is three years later and there's not a second that goes by that Brittany's not on my mind," said Brandy Reynolds, Hart's sister.

When sex offender Robert Carson grabbed a hammer and beat 24-year-old Brittany Hart to death in his Spring Valley home, nobody proposed a one-strike law or lifetime GPS monitoring for sex predators.

"It's horrible. It took Brittany and Chelsea and Amber to finally get somebody to listen and do something about these monsters," Reynolds said.

Reynolds will never know why there was no call to action after the murder of her sister, but she's ready to fight now for Chelsea's Law.

"Any support I can offer, anything I can do to help push it along, protest, whatever it is; we have to protect innocent lives out there," she said.

Hart's murder is all too familiar in light of the recent arrest of convicted sex offender John Albert Gardner, III.  Gardner is has pleaded not guilty to the rape and murder of Poway High School senior Chelsea King.  He also is a focus of the investigation into the death of Escondido teenager Amber Dubois.

Robert Carson lured Brittany Hart to his home in May of 2007. Search teams spent three weeks looking for the missing woman before her body was found soaking in acid inside a trash can in the East County.

"My kids still ask for Aunt Brittany and why did the bad man take her," Reynolds said.

Like accused killer John Gardner, Carson also had a history of sex crimes.

In 1986 a jury found Carson guilty of attacking four women. One was tackled on the street in Grantville and beaten, another woman was sexually violated in a Mission Gorge carport. He exposed himself to a nurse at Mercy Hospital, and tried to rape a woman in a Mission Valley restroom.

Carson was sentenced to 17 years in prison, but only served nine. Like Gardner, Carson violated parole no fewer than six times. Once off parole, he groped a woman in the Gaslamp Quarter and was sentenced to probation after pleading guilty to a misdemeanor.

At the time of Brittany Hart's murder in 2007, Carson was free on bail and facing felony charges after leading officers on a wild, methamphetamine-induced chase through Coronado.  He later pleaded guilty in that case.

"There are so many similarities between Gardner and Carson it is baffling," Reynolds said.  "And how they let these monsters back out on the streets, I will never understand."

Robert Carson pleaded guilty to murder to avoid the death penalty and received 91 years to life in prison.  He currently is being evaluated at the Donovan Correctional Facility in Otay Mesa, but will soon be transferred to another state prison.

Supporters of Chelsea's Law are calling for one-strike life sentences, better handling of parolee records at the state level, and increased GPS monitoring for all violent sex offenders.