It's not easy to shock Dave Schroeder anymore.
For more than a decade the 45-year-old Kansas Bureau of Investigation agent has been culling images of child pornography, threatening letters and bizarre diaries from personal computer hard drives.
"I always thought there was a fair share of people out there who were perverted, but working these cases, the general public does not realize the magnitude of it," Schroeder said.
Schroeder is one of four agents on the KBI's High Technology Crime Unit assigned to investigate computer crimes. In 1998 he took part in an international investigation called Operation Cheshire Cat headed by the U.S. Customs Service.
The operation led to numerous arrests of suspected child pornographers operating over the Internet. One of them was a Lawrence man.
"I try to distance myself from it, but sometimes I still see things that you just can't believe are out there," Schroeder said.
At any given time the high tech unit has about 20 cases pending. Currently, agents are working to unravel computer information in 19 cases from across the state. Fifteen of them involve child pornography or sexual exploitation of a child. The remainders are sexual assault or homicide cases.
"Any type of crime you can think of, there has probably been a case that involved a computer," Schroeder said.
Schroeder and other agents can't discuss pending cases. Last summer, however, Topeka Police asked the KBI to examine computers belonging to double homicide victims Karen K. Harkness, 53, and Michael Sisco, 47.
In general, homicide suspects or their victims may have threatening e-mails or other written documents on their computers linking them to the crime that could be used as evidence, said Rick Sabel, agent in charge of the cyber sleuths. Because computers are becoming so prevalent, more of them are being seized for examination with search warrants.
"It (the computer) is potential evidence, and there is a reasonable expectation that there is some evidence there," Sabel said.
Working out of offices in the KBI's Topeka headquarters, agents first make copies of a seized computer's hard drive. The original hard drive is stored into evidence, and the search for images and other data is conducted on the copy.
The time needed to search through hard drive data depends on how much data has been stored, Sabel said. Although most hard drives aren't nearly full, there could be enough information on a hard drive that, if printed on paper, would fill more than one good-size room, he said. Some cases involved searches of multiple hard drives, he said.
Unless a computer user is an expert, he or she doesn't know how to completely delete what has been on the hard drive, Sabel said.
"It's not so much that it is difficult to find, it just takes a lot of time," Sabel said of computer evidence.
Two years ago a Kansas Lottery employee was arrested after a KBI investigation revealed how he altered the lottery's computer system to turn losing tickets into winning tickets.
It took six weeks of painstaking effort to search through back-up lottery scratch-off ticket computer files to come up with the evidence, said Schroeder, who led that investigation.
The state was tipped off to the scam by a couple of store clerks in Johnson County who became suspicious of what appeared to be mutilated tickets coming up winners when they ran them through the store's computer, Schroeder said.
Except for special fraud cases such as the lottery scandal, the KBI has had to restrict its computer crime investigations to cases involving crimes against people. Requests come in almost daily for the KBI to investigate Internet fraud and identity theft.
"There are too many of them, and we can't work them," Sabel said. "We just don't have the resources. If you are a violent crime victim, you want that handled before a fraud case."
Computers and the multiple software programs they use are becoming more complex, Sabel said. Continuous updating of expensive equipment is needed to help solve cases involving computers, he said. A little more than a year ago the KBI spent $20,000 buying new equipment.
"In a matter of a year or so we have to upgrade this stuff, and the expense is just tremendous," Sabel said.