DNA, when used correctly, can be an extremely useful tool when it comes to matching a suspect to a crime.

In many of the cases we've covered, the reason that it went cold was because the DNA technology we used now wasn't available to the original investigators.

This is one of those cases.

The original detectives used the investigative tools of the time,

but they simply weren't able to connect the killer to the crime.

Cold case units, like the one in Fairfax County, Virginia,

apply today's science to previously unsolved cases.

From A&E, this is Cold Case Files.

I'm Brooke, and here's the impeccable Bill Curtis,

with a classic case, a knock at the door.

Thank you. Here's the impeccable Bill Curtis with a classic case and knock at the door. This is the Cold Case Homicide Office. It's part of the homicide squad in Fairfax County Police,

and this is where we store a number of the cases that were...

Steve Moleski and Bob Murphy are cold case detectives for Fairfax County, Virginia.

These photographs only represent a small number, and we were...

Packed to the wall of their squad room, the faces of some of their victims.

It's sort of matter of respect to these people that they're here,

and it's our responsibility to find answers to their deaths.

Any homicide detective will tell you they have their cases that are really at the top of their list of what they would like to solve.

One of those for me is this one, it's a double homicide of a couple here in Vienna, Virginia, back in 1997, and this case is still open.

This little boy here was found dead, naked and dead in a stream in Fairfax County in

1972, I believe it was. We have no idea who he is, just a little boy. He's maybe four to six

years old. In the winter of 2004, Murphy and Malewski pulled out the picture of another victim.

...