"We look at the videotape and you've got to slow it down and take the people out if it so that you're not just concentrating on the act that's happening but on everything going on around it," said Detective Janet Sobotka, who works with McGarry at the child exploitations unit in Toronto. "And if worse comes to worse, you put it on the news to see if anyone can recognize [the image]."
Sometimes the public's knowledge of a particular place or person can be investigators' key clue to find a victim or an offender, Sobotka said, further emphasizing that media exposure can be a great help in child porn cases.
Nevada authorities have now released still images of the missing girl, the person of interest and the man who turned the tape over to authorities. Media outlets have published these photographs, along with tip line telephone numbers, in case viewers can help the investigators identify the victim and her offender.
During the press conference, Nye County authorities expressed their gratitude to the American public, many of whom have already "inundated" the police department with tips.
Determining the manufacturer of the material items caught on tape, said McGarry, is another method that often leads investigators directly to the victim. McGarry remembers once case he worked on was able to locate a young female victim after discovering the dress she was seen wearing in the video was a school uniform. McGarry then contacted the uniform manufacturer who told him which schools ordered the clothing.
Similarly, Nevada authorities have tracked down the manufacturer of the lingerie worn by the missing girl to a manufacturer in North Carolina.
When your job involves pouring over thousands of sexually explicit child pornography tapes for weeks on end and often making little headway, the toll it takes on your mental state, as well as your personal life, can be difficult, investigators told ABCNEWS.com.
"We all have the responsibility to look after each other," said Sgt. Kim Scanlan, who oversees 15 investigators in the child exploitation unit in Toronto. "We try to do the occasional outing to make arrangements to go golfing or do something fun so we can kind of break the tension after a long session of viewing a lot of children porn. It breaks up the tension and gets people to think about something else."
For McGarry, who has a wife and children of his own, the satisfaction of finding a victimized child is worth the grueling hours spent viewing the tapes.
"We keep in mind that the ultimate goal is to find the children," said McGarry, who added that he has become "hyper-vigilant" of his own children. "If you can keep that in perspective it keeps you going and there is great satisfaction when you actually find a child."
Sex crime investigators are required to get psychological evaluations, and meet with therapists who evaluate how they are coping with their jobs every six months.
When asked what the worst part of her job is, Sobotka, who no longer watches as many tapes as she used to thanks to a promotion, answered "frustration."
"There are certain [children] that stick with you," said Sobotka. "There are certain images or certain children that you think about. It's frustrating not being able to help each and every one of them and [not being able] to prevent it from happening to other children."