Both departments rely heavily on individual investigators' judgments, and they follow similar procedures for collecting, storing and retrieving evidence. The movement of rape kits among crime labs, property rooms, clerical personnel, detectives and prosecutors is painstakingly documented.
In the Sheriff's Department, detectives, in writing their initial crime report, assign evidence a "retention" number, which usually refers to the length of the statute of limitations.
About every six months, personnel in the department's property and evidence unit in Whittier ask for instructions on what to do with the evidence. The unit has three 20-by-40-foot freezers where biological evidence is stored and will soon have a fourth.
Detectives tell the property room to save the evidence or destroy it. They are not required to give any explanation for their choice, Zavalo said.
"The case investigator is responsible, because they should be, and are, aware of what's going on with the case," he said.
At the LAPD, a supervisor must approve a detective's decision, Ward said.
The authorization is given monthly on a "disposition summary" document that detectives receive from the property and evidence unit. Ward said that whoever approves the disposal of evidence is expected to review the case file or consult with any former detective assigned to it before authorizing disposal.
Johnson, the support services administrator, said unneeded evidence has to be thrown away periodically to save space.
"We definitely have space problems," she said. The property room, which is on Ramirez Street, will soon add about 2,000 square feet of freezer space to the 3,000 it already has. Even with that, she expects the unit to run out of space before the end of the year if the moratorium continues.
The California Department of Justice maintains two computer databases of DNA evidence, one with more than 224,000 DNA profiles of people convicted of sexual offenses, domestic assault, certain robberies and other crimes. Although the database was established in 1994, it didn't become large enough to be useful until about 18 months ago, according Frank Fitzpatrick, director of forensic services for the Orange County Sheriff's Department.
The state also maintains a database of DNA material collected from unsolved sex offenses. The two databases permit investigators to cross-check DNA profiles in unsolved rapes with the profiles in the database of criminals.
As the number of DNA profiles in the databases increases, detectives have a greater chance of finding rapists. That's why the new statute of limitations law that went into effect in 2001 is so important, experts say.
At the very least, the law extends the time limit from six years to 10. It allows the investigation to continue without any deadline for sex offenses committed after Jan. 1, 2001, if the DNA is analyzed within two years of the offense.
For crimes committed before 2001, the biological evidence must be analyzed before 2004 to put the statute of limitations on hold.
The statutory clock will not start ticking again until the DNA has been conclusively matched with a suspect, at which time authorities have one year to begin prosecution.
Rape survivors say the new law, combined with rapid scientific advances, has made the destruction of biological evidence and the huge backlogs especially egregious. For them, it means law enforcement has frittered away opportunities to solve cases and stop countless other sex offenses.
The Rainbow Sisters will hold a "DNA Awareness March and Rally For Public Safety" in front of Los Angeles police headquarters at Parker Center to, among other things, protest the destruction of rape kits.
"This is a core safety issue," said Jeri Elster, a rape survivor and member of the group.
Even if a rape kit cannot be used to prosecute the case for which it was meant, the DNA profile could help stop the rapist if he is charged with a subsequent offense, said Lisa Kahn, a prosecutor who heads the Los Angeles County district attorney's forensic science unit.
"It can be used as corroborative information," she said.
More than that, Kahn added, rape survivors need to know if their attacker has been caught.
"From a purely humanistic view point," Kahn said, "if you can someday tell a victim, 'Hey, we've caught the guy, we're prosecuting him, and we're going to put him away for a long time,' it gives them some relief."
Patti Lancaster, the 1992 rape survivor, agrees. "To know he is in prison would make me feel fabulous," she said.
"Just this morning on the set [for a commercial shoot], one of our people had the cologne that was so similar to his," she said, referring to the rapist.
"It was a reminder of the incident," she said. "That he's still out there. That it can happen again."