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To determine the character and traits of an unknown offender, profilers analyze evidence left behind at a crime scene, McCrary explains.
"The goal is to help law enforcement develop suspects and prioritize the ones they have," says McCrary, who retired in 1995 after a 25-year career with the Bureau. "There is always going to be some skepticism about what we do," he adds, "but if it wasn't working, there wouldn't be a demand for it. Surveys we've done show 70 to 80 percent of law enforcement say our work was helpful."
Profilers also utilize victimology, the study of why certain people and lifestyles affect the chances of falling victim to a crime. But according to McCrary, street prostitutes are among the hardest to study, owing to the number of strangers they meet. He also claims they are among the easiest and most frequently targeted victims.
"In my experience," says Captain Andreu, "every serial killer has a mental picture of an ideal victim, someone who has a certain look, hair color, age. Generally that person doesn't come into their circle so they take the next best thing. Street prostitutes make easy victims. Most of them have drug problems, offer them $100 and their eyes will get so big they will hop in a car and let someone tie them to a tree if they're asked. They need the money."
Indeed, like the "suitcase murderer," some of the most notorious serial killers of all time have preyed on prostitutes, among the worst the "Green River Killer," Gary Leon Ridgeway, who butchered 48 Seattle-area women beginning in 1982. "I picked prostitutes," he said during his trial in 2003, "because I knew they might never be reported missing.... I thought I could kill as many of them as I wanted without ever getting caught." Ridgeway's murder spree lasted more than two decades despite the assistance of the FBI's best profilers.
In the twelve months following the Dietz and Demas murders, on the FBI's advice, South Florida investigators followed up on more than 250 leads. Det. David Frisbie says they spent more than a thousand hours combing pockets of Biscayne Boulevard between 36th and 79th streets known to be frequented by prostitutes. Investigators questioned every woman they met in the hope of procuring even the slightest nugget of information. Each girl was photographed and given a questionnaire to document her life on the streets.
"These women live in a brutal world," says Frisbie. "We'd take a picture of every girl and be back out there six months on and with the drugs, and alcohol, and getting beat up, we wouldn't even recognize her any more."
Tips were sparse. "We played every scenario over and over again, going through every minute detail," says Frisbie. "We literally went over thousands of possibilities."
When the leads dried up, investigators tried a different approach.
"We'd do john stings with the Miami police and question everyone regular guys, doctors, lawyers, anyone," Frisbie explains. "We took a DNA sample from each one and filed it away."
They left business cards with motel managers and street people. They contacted Interpol to check for similar cases committed overseas. They tracked down registered sex offenders in the area and knocked on their doors. They ran the two murders through the FBI's Violent Crimes Apprehension Program (VICAP) a nationwide database of crimes and victims to check for similar murders in other states. Cooper City police even gave a presentation to 30 South Florida police stations to see if any of the details might spark a new lead.
"We'd get a lead and get all fired up thinking this was our guy, then through DNA or fingerprints he was eliminated," says Frisbie.
One tip led police to the Knight's Inn at 3580 Biscayne Blvd., where manager Maria Rivaflecha claimed to have seen Dietz the night before she was killed. She also claimed to have found a grapefruit-size blood stain on the carpet of room 133.
Police descended on the motel, tore up the light green carpet, and painstakingly dusted each room for hairs and fibers.
Then Rivaflecha handed police another clue, the name of another local at the motel: 21-year-old Sia Demas.
Demas was born in Chicago but as a young girl relocated with her family to Hollywood, Florida, where she was raised.
Her mother, Pam Saiger who declined an interview with New Times described her daughter to local media as a sensitive girl who would bring home stray cats and dogs.
"Once she even brought home a stray man," Saiger told reporters. "She said, 'Mom, I feel sorry for him.'"
Saiger claims her daughter began abusing drugs as a teenager, grew addicted to crack, and eventually dropped out of high school. A string of arrests in Broward and Miami-Dade counties followed, for prostitution and possession of cocaine and drug paraphernalia.
"Sia first came before me as a juvenile," recalls former Broward County Circuit Court Judge Melanie G. May, who presided over at least three Demas hearings. "I saw her many times over the years. She had a very supportive mother who also pleaded with me to give Sia another chance." Judge May, who left for the Fourth District Court of Appeal in 2002, says she got to know the five-foot-seven brunette well over the years. "To be quite honest, I felt sorry for her. She wasn't particularly attractive and always seemed so uncomfortable in her own skin."