You may think you deleted that file from your computer. You might think emptying the recycle bin will erase it forever.
But deep in the recesses of your hard drive, the file remains intact and can be found — by someone who knows how to look.
The same is true for any device that stores data electronically, such as printers, cell phones and answering machines.
That saved one Oklahoma City detective who accidentally deleted a key confession from a voice recorder, said Oklahoma City police Sgt. Rob Holland, who heads up the computer forensics unit. Holland was able to find and restore the deleted file using special software.
Computer forensics is becoming a key component of solving crimes, but not just computer crimes, said Patrick Kennedy, lead computer forensics agent with the Oklahoma State Bureau of Investigations. Electronic evidence has helped solve murders, rapes, robberies, child pornography cases and even has jailed a few officials.
"We're more than doubling our caseload each year,” Kennedy said. "People are becoming more computer savvy, and computers are more and more embedded in people's everyday lives.”
Clues for law enforcement
In years past, investigators would have to dissect only one computer with a 20 gigabyte hard drive; today they typically confiscate several computers with much larger hard drives. The amount of data they must sift through is often "daunting,” Kennedy said. But increasingly it's a necessary job.
More than half of all computer-based cases involve child pornography, Kennedy and Holland said. And in nearly every case, digital evidence can be extracted and used to prosecute, Holland said.
When homicide detectives have exhausted all leads, they might look at e-mails sent by the victim, what cell phone calls were made or even the person's Internet history, Holland said.
Such was the case in Weleetka, where Taylor Paschal-Placker, 13, and Skyla Whitaker, 11, were shot to death June 8 on a rural road.
Investigators confiscated several computers the girls might have used to determine whether they could develop any leads, Kennedy said.
He would not say whether the computers have aided in the investigation, but said it never hurts to have one extra tool.