ST. CHARLES COUNTY • Detective Chris Bosley is 6-foot-5, weighs 300 pounds and sports a bushy red beard, but he poses online as a 13-year-old girl.
Bosley, a former Marine, is one of three investigators for the St. Charles County Cyber Crime Unit, which is marking its 10th year of operation.
Bosley, 34, gets through a day of trolling for sex offenders by keeping a good sense of humor and a pack of Post-it notes handy so he can place them over body parts on X-rated webcasts.
"I don't talk to my family about what I do," he said. "They just know that I arrest monsters."
Bosley actually has five different personas online. One of them is a teenage boy, although most of the people he encounters seeking sex on the Internet are heterosexual men, he said.
He keeps cheat sheets handy for quick reference about clothes sizes or any other questions he may get, including bras and birth control.
"Sometimes if I can't find the sheet, I have to scream across the room to figure out what size clothes I wear," he said.
The unit is one of nine task forces in Missouri dedicated to investigating crimes against children online. It's staffed by officers from the St. Charles and Lincoln county sheriff's departments and the O'Fallon, Mo., Troy, Mo., and St. Peters police departments.
Bosley and other investigators work in nondescript cubicles that might be found in the middle of any office — except that they are equipped with multiple computers, so investigators can work several leads in different chat rooms at the same time.
The unit is funded through local, state and federal grants as well as a budget from the St. Charles County Sheriff's Department. Drug forfeiture money has also been used to buy equipment, such as a mobile cyber lab, a van where computers and other electronic devices can be evaluated.
The unit consists of three investigators who follow leads about child-related crimes, and three examiners who recover the evidence from computers and other electronic devices.
They handle cases primarily in St. Charles, Warren and Lincoln counties, but they regularly cooperate with agencies from across the state and country, said Lt. Chris Mateja, supervisor of the unit. The average case takes approximately 42 hours to complete, and their caseload has increased every year. Last year the unit investigated 327 cases and played a part in 67 arrests or indictments.
While most of the crimes they investigate involve adults trading child pornography, the examiners also recover electronic evidence used in cases such as one in which a woman was accused of harassing a teenager online. The woman was acquitted last week.
They also recover evidence in theft cases and death investigations. Mateja said that sometimes thieves will use Google maps or GPS devices to plan their routes to houses they burglarize.
As for deaths, sometimes computers help verify the intentions of the deceased.
"A person had died, and we really didn't know the cause of death, so we went through the computer and we saw through his Internet history that he had been researching antifreeze," he said.
Based on the information, the medical examiner did a toxicology screening for the chemicals in antifreeze, and it confirmed that that was how the man had killed himself.
Because the computer examinations require a lot of technical skill, most of the police officers trained for and assigned to the unit remain there for years. That also goes for the officers who chat online, which takes a more social set of skills.
Detective Marsha Corley said that the more she posed online as a teenager, the better she got at the story lines that go with her personas.
Corley, 56, is a mother of four grown children, and she draws on real-life experiences in her work. Sometimes she uses some of her sons' attributes when she describes a "boyfriend" to a potential offender.
Investigators have to follow certain rules online, Corley said; for instance, she can't initiate contact with someone. If they want to see a photograph, she scans in a picture that might be hers from her teen years or that of another police officer.
When someone sends her an instant message, she tells the person right away that she is 14.
"Seventy-five percent of them will go away at that point," she said. "Some of them might even tell me to be careful. But if they keep talking to me there's a pretty good chance the conversation is headed toward sex."
Corley said most of the people she chatted with were not interested in meeting in person for sex; they prefer a video hookup.
She said she had never had to face the criminals she investigated in court because almost all of them agreed to take a plea agreement rather than go to trial.
Many of those charged have traded child pornography, and it's Detective Tony Stewart's job to watch the videos so he can accurately describe them for the record.
"The first couple of cases I worked were difficult because I don't think I had mentally prepared myself for what I was going to see," he said.
Stewart, 32, said listening to his iPod while watching the videos helped him to cope, as did the support of the other members of the unit.
Mateja said investigating child-related crimes was not for every officer, but the proliferation of electronic devices means cyber evidence is here to stay.
"Everybody's got a cellphone now, so every officer now has to consider that electronic component," he said.