SAN DIEGO -- The parents of slain Poway High teenager Chelsea King and a state assemblyman unveiled a proposed law in Sacramento Monday to strengthen penalties for forcible sex crimes and tighten monitoring of offenders.

Chelsea, a cross-country runner, was out for an after-school run near Lake Hodges Feb. 25 when she was allegedly raped and killed by convicted sex offender John Albert Gardner III.

Her parents, Kelly and Brent King, went to the state capital accompanied by Assemblyman Nathan Fletcher, R-San Diego.

"Today is the day we start our race," Brent King said at a news conference before departing. "It's a race Kelly and I didn't choose to run in. We were selected to run in it."

Tonight, supporters will take a bus to join them. The 57-passenger bus will leave from North County Fair at 7 p.m. and will return around 7 p.m. Tuesday, according to King family spokeswoman Sara Muller Fraunces. The ride is free, but the King family is asking for donations to tip the driver, she said.

On Tuesday, the Kings and their supporters are expected to carry more than 1,000 sunflowers onto the east steps of the capitol. The 11:45 a.m. event, dubbed Sacramento Sunflower Ovation, was organized via Facebook and timed to coincide with the formal introduction of Chelsea's Law.

Chelsea's Law would mandate stricter sentencing guidelines for violent sex offenders and institute more intensive monitoring of parolees. The bill calls for mandatory life sentences for certain violent attacks and life-long GPS tracking.

The measure would fill gaps in existing law, San Diego County Sheriff William Gore said at the news conference.

"It allows us to hopefully deter these people from making further crimes, but if they do it helps us make a quick apprehension."

Chelsea -- a straight-A student, athlete and musician -- was found in a shallow grave five days after she was reported missing.

Gardner, 30, was registered as a sex offender in Lake Elsinore, but had been staying with his mother in Rancho Bernardo, near where Chelsea was slain.

Ten years ago, Gardner pleaded guilty to sexually assaulting a 13-year-old neighbor girl at his mother's home in Rancho Bernardo.

A psychiatrist recommended Gardner receive the maximum sentence of 30 years in prison, but the District Attorney's Office made a plea deal to spare the victim from testifying at trial. Under that deal, Gardner served five years of a six-year sentence.

Since Gardner's arrest in Chelsea's case, state corrections officials have revealed that Gardner racked up seven parole violations during the three years he was on parole from the 2000 attack but none were significant enough to send him back to prison.

Detectives are also looking at Gardner in the disappearance and apparent murder of 14-year-old Amber Dubois, whose body was found March 6 -- more than a year after she was reported missing after last being seen walking to Escondido High School.

A preliminary hearing for Gardner in Chelsea's killing is set for Aug. 4.

The bill introduced by Fletcher calls for life imprisonment without the possibility of parole for any forcible sex crime against minors that include one or more aggravating factors, including the age of the victim, whether a kidnapping substantially increased the risk of harm, the perpetrator has a previous forcible sex crime conviction, and whether he tied, bound or drugged the child.

The measure would also double the maximum penalty for a forcible sex crime to 16 years in prison, prohibit a convicted sex offender from entering a public park where children regularly congregate without prior approval of a parole agent, double the period of parole to 10 years for all forcible sex crimes, and establish lifetime parole and GPS monitoring for offenders who commit such crimes against children under 14 years old.