( CNN ) -- Two registered sex offenders are accused of raping and killing four women in Southern California while the men were wearing GPS ankle-bracelets , authorities say . `` The GPS was in fact intact , attached to these suspects during the commissions of the crimes , '' Anaheim Police Chief Raul Quezada told reporters Monday . Steven Dean Gordon , 45 , and Franc Cano , 27 , were scheduled to be arraigned Tuesday , but the hearing was postponed until May 19 at the request of a defense attorney , authorities said . The two men were arrested Friday night . Their ankle monitors and the women 's cell phone records helped authorities link the cases to the suspects , police said . The body of Jarrae Nykkole Estepp , 21 , of Oklahoma , was found at an Anaheim recycling plant on March 14 , Anaheim police said . The disappearances in Santa Ana of the three other women are being treated as homicides , although their bodies have not been found . Kianna Jackson , 20 , was last reported seen on October 6 ; Josephine Vargas , 34 , on October 24 ; and Martha Anaya , 28 , on November 12 . Both men had been convicted of sex crimes involving children : Gordon in 1992 and Cano in 2007 . Each man had checked in with police every 30 days , as required , and authorities had no reason to watch them more closely , Anaheim Police Department spokesman Lt. Bob Dunn said . A state Department of Corrections official would not say what authorities may have known about the suspects ' activity . `` Due to the complexity of the investigation , we are not at liberty to speak on those , but , however , the questions are coming forth to headquarters in Sacramento and , as time permits or we 're allowed to , they will respond to your questions , '' Charles Dangerfield told reporters . All the women are believed to have worked as prostitutes , police said . Sex offenders routinely released from California jails , records show . CNN 's Michael Martinez and Stella Chan contributed to this report .
NEW : The two sex offenders ' arraignment on new charges Tuesday is postponed . Suspects Steven Dean Gordon and Franc Cano are convicted sex offenders . Gordon was convicted in 1992 ; Cano in 2007 . Both were wearing GPS monitors during the killings , police say .