ANAHEIM, Calif. (AP) -- Two convicted sex offenders dutifully checked in with police every month and wore their GPS trackers around the clock - the rules of parole that are designed to tip off authorities if a freed felon backslides.
Yet for at least two months last fall, authorities claim, Franc Cano and Steven Dean Gordon were raping and killing at least four women - and probably a fifth - in the seedy prostitution hangouts of Orange County.
It was data from their GPS trackers - along with cellphone records from the victims and other evidence - that helped investigators link them to the killings, police said.
"That was one of the investigative tools we used to put the case together," Anaheim Police Chief Raul Quezada said at a news conference Monday.
Cano, 27, and Gordon, 45, were arrested by investigators on Friday. Each was charged Monday with four felony counts of special circumstances murder and four felony counts of rape.
If convicted, they could face a minimum sentence of life without parole or the death penalty. They were being held without bail and expected to be arraigned Tuesday.
The men had known each other at least since 2012, when they cut off their GPS trackers and, using fake names, fled to Las Vegas, where they stayed at the Circus Circus Hotel & Casino for two weeks before they were rearrested, according to documents filed in U.S. District Court in Nevada.
While out on parole, police believe the men killed three women in Santa Ana last October and November and an another woman in Anaheim earlier this year. All had histories of prostitution.
Quezada said authorities were confident that there was at least a fifth victim and perhaps more.
Investigators "put a stop to a serial killing that would likely have continued beyond this point," District Attorney Tony Rackauckas said.
The department has contacted other places with missing-persons cases across the country.
Kianna Jackson, 20, of Las Vegas, arrived in Santa Ana the first week of October for a court hearing on four misdemeanor charges of prostitution and loitering to commit prostitution. Her mother said she stopped responding to her text messages soon after she arrived in Santa Ana.
She checked in to a Costa Mesa hotel but never paid the bill nor checked out, and her belongings were found there.
Josephine Monique Vargas, 34, was last seen Oct. 24 after leaving a family birthday party in Santa Ana to go to a store.
Martha Anaya, 28, asked her boyfriend to pick up their 5-year-old daughter so she could work on Nov. 12, then stopped responding to his messages later that night. She had been planning a birthday party for her daughter.
Santa Ana investigators didn't realize that they were looking for murder victims at first, Police Chief Carlos Rojas said.
Instead, police considered them missing persons. Investigators searched a canyon, examined the women's cellphone records, alerted hospitals, put the word out on social media and even checked motels they were known to frequent but without success in finding them.
Then, on March 14, the naked body of Jarrae Nykkole Estepp, 21, was found March 14 on a conveyor belt at an Anaheim trash-sorting plant.
That was the key that broke the case, authorities said.
In the weeks before the discovery, Estepp had become a regular on a strip of Beach Boulevard in Anaheim long known for prostitution.
Estepp had "a similar profile to our victims; we were able to ... move forward," Rojas said.
Investigators planned to search for the bodies of the three Santa Ana victims, he said.
Cano and Gordon each served time after being convicted in separate cases of lewd and lascivious acts with a child under 14.
Gordon was convicted in 1992 and has a 2002 kidnapping conviction, according to the Orange County district attorney's office. Cano's conviction dates to 2008, prosecutors said.
After their Las Vegas escapade, Cano and Gordon pleaded guilty to failure to register as a sex offender. They were ordered to provide DNA samples and have their computers monitored by federal agents, according to the federal documents, which were first obtained by the Los Angeles Times.
The men also checked in with Anaheim police every 30 days, as required, and provided updated photos, fingerprints and addresses, Anaheim police Lt. Bob Dunn said.
In fact, both men checked in earlier this month, Dunn said.
Cano was wearing a state-issued ankle monitor and Gordon was wearing a federal GPS device, he said.
Associated Press writers Anthony McCartney and Daisy Nguyen in Los Angeles and Amy Taxin in Santa Ana contributed to this report.
MIAMI (AP) -- Tied to an unpopular president and his signature health care law, Democrats in the nation's largest swing state see medical marijuana as a potential antidote to political malaise in this year's midterm elections.
Party operatives are pushing a constitutional amendment that would make Florida the first state in the South to legalize some pot use. Polls show the measure has widespread public support, and it's particularly popular among young voters - a critical part of the Democratic coalition with historically weak turnout in non-presidential election years.
"I wish that it didn't take medical marijuana on the ballot to motivate our young voters," said Ana Cruz, former executive director of the Florida Democratic Party. "But listen, we'll take it any way we can get it."
Activists are also gathering signatures for medical marijuana initiatives in Arkansas, where Democrats are fighting to retain the governorship and a U.S. Senate seat, and Ohio, where the party is trying to oust GOP Gov. John Kasich. But those petition drives face significant organizational hurdles.
The political world likely will be focused on Florida in November for clues about the turnout potential among young voters of pot on the ballot. At stake is the governor's office, as well as a handful of competitive House seats.
In 2012, both Washington and Colorado saw spikes in youth turnout when marijuana initiatives were on the ballot. This year, Florida could be a critical test case for whether those increases were an anomaly or the start of a trend in advance of the presidential election in 2016, when activists plan to launch legalization campaigns in at least six states, including battleground Nevada.
"It's a smart move on the Democrats' part," said David Flaherty, a Colorado-based GOP pollster. "It's going to help them, no doubt about it."
Florida Republicans argue that Democrats do not have a clear-cut advantage on medical pot, with public polls showing an overwhelming majority of GOP voters supporting it. They also say it's unlikely to excite young voters in the way that legalization campaigns did in Colorado and Washington, where pot was sanctioned for recreational use along the lines of alcohol, or become part of a divisive culture war that could drive turnout.
Nevertheless, the marijuana initiative may be one bright spot for Democrats in an election year that could be grim for the party. President Barack Obama remains unpopular, and Republicans are trying to make the elections a referendum on his health care law. Gov. Rick Scott is making the health care overhaul a central issue in the governor's race and outside conservative groups, such as Americans for Prosperity, are funding a barrage of negative ads against Democrats in a handful of swing-voting House districts.
"I would rather have it on the ballot than not," said Steve Schale, a Democratic consultant who managed Obama's Florida campaign in 2008. "It could have a marginal impact, and a marginal impact in Florida could be the difference between winning and losing."
A Republican victory in a special House election last month in Florida underscored the Democrats' turnout problem. The St. Petersburg-area district has 2.4 percent more registered Republicans than Democrats, but GOP voters outnumbered Democrats by 8 percentage points among those who cast ballots.
Some Republicans paint the medical marijuana initiative as a ploy by Democrats to help former Gov. Charlie Crist, a Republican turned Democrat, reclaim the governorship. Crist supports the measure, saying it's "an issue of compassion." Scott opposes it, citing his brother's struggles with substance abuse.
The marijuana campaign's chief financier is John Morgan, an Orlando trial lawyer and major Democratic donor whose firm employs Crist. Morgan insists the effort is personal, not political; he says marijuana eased the suffering of his father, who died of esophageal cancer, and his brother, who is a quadriplegic.
Democrats say the medical pot measure could help counter Republican energy by motivating young and independent voters. According to a national survey sponsored by George Washington University last month, nearly 40 percent of likely voters said they would be "much more likely" to vote if a legalization measure was on the ballot, with another 30 percent saying they would be "somewhat" more likely to vote.
Organizers of the medical marijuana effort plan to raise and spend $10 million on their campaign, with much of the money devoted to a turnout operation aimed at registering voters to cast absentee ballots.
"We want to be able to have our stereotypical, lazy pothead voters to be able to vote from their couch," said Ben Pollara, a Democratic fundraiser and campaign manager for the United for Care group, which also plans to get voters to the polls on Election Day.
Associated Press news researcher Judy Ausuebel contributed to this report.
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