Young men shipped off to war would never return. Forensic experts work to tell their stories.

This episode begins by showing how forensic scientists work backwards from a confession to concrete evidence. Before progressing to why cold cases shouldn't be forgotten about. It does not matter if it is minutes or years after the crime, these experts work to tell the stories of the victims.

Scientists explore the differences between targeted and random poisoners, and the significance of disguising a targeted act of poison as a random act, such as the Tylenol case in Chicago.

Journey into the dark recesses and calculated madness present only in our worst nightmares; and in the minds of serial killers, such as Richard Chase - The Vampire Killer of Sacramento, Mike DeBardeleben - The Mall Passer, and John Wayne Gacy - The Killer Clown, to name just a few. Renowned FBI profiler Robert Ressler can reveal unseen clues about a killer simply by learning details about the crime. Investigative profiling discloses a killer's hidden motives.

Forensic photographers are amongst the first people at a crime scene, capturing vital clues on film. What do the cameras capture that can't be seen first-hand and who are the men and women who analyse these camera clues?

With DNA analysis just a few microscopic cells found at a crime scene can be used to convict a killer. Forensic scientists can analyze droplets of blood, hair fiber, or a piece of chewed gum to determine the identity of a victim or killer -- or to prove innocence.

Forensic Entomology: Bug have been around for millions of years. Their habits surrounding death can tell these experts when the victim died.

Forensic Sculpting: These experts can take nothing more than their knowledge, clay, and a skull and bring the victim to life. Once nameless victims can now have a name.

Missing Person: In America nearly 1.8 million people are reported missing each year, factor in the world and that number triples. Using computer databases and other means victims are found, laid to rest…or never seen again.

Identifying Burned Remains: Murder is hard to prove with no body, when the victim has been burned it is even more difficult. Fire does more than destroy evidence . . . it can keep the secrets you don’t want anyone to know.

Explosives Investigations: A woman opens a box which explodes killing her. Soon to follow are five other bombs just as deadly as the first. This soon turns into a massive investigation leaving the experts to sift though the evidence.

Fingerprinting: The backbone to forensic science, the fingerprint is a very effective way to identify victims and criminals. Not only are fingerprints used but also palm prints and foot prints. Data entered into massive databases make identifying people easy…when there is a hit.

Handwriting Analysis: Every pass of the pencil leaves a little of ourselves behind. Taking the time to evaluate documents can tell the difference between suicide and murder.

Black Boxes: A plane plunges toward the ground and upon impact little remains. The only possible survivor is the flight data recorder. This little black box could hold the answers to the last terrifying minutes.

Forensics in the O.J. Simpson Murder Trial: The verdict is in Not Guilty of murder. O.J. Simpson emerges a free man. What was the evidence and could it be trusted? These experts break down the evidence could and could not tell us.

Ballistics: A body with a gunshot wound to the head, the gun is next to the body. Was it suicide or murder? Every part of the gun can be analyzed for the correct answer.

Forensic psychologists delve into the minds of serial killers, explaining why, most often, they can be a friendly neighbor or a tenacious co-worker – the ones who hide their darkness better than anyone else.

It is difficult to convict a murderer if the body can’t be found, but forensic science is finding ways to do it. A speck of blood, a piece of a fingernail or a strand of hair may now be enough evidence to prove a murder and capture a killer.

Observing how the smallest bits of forensic evidence, such as carpet fiber or an eyelash, can seal a case. Included: how strands of hair indicted a killer.

Plants help provide oxygen and nutrients for existence. In criminal investigations, a simple seedpod can provide the missing link by placing a suspect at a crime scene. Dirt left on shoes, tires or clothes can pinpoint a crime scene.

While drugs can cure disease and ease pain, they can also be agents of murder. Toxicologists can examine blood and tissue to uncover cases where death is not as natural as it may seem – from slow arsenic poisoning to quick cocaine overdoses.

A tool used to commit a crime can often be the same tool used to solve it. The pattern a machine leaves on an item, the unusual way a tool crimps a wire and even something as innocuous as the shape of a wood chip can lead to a killer.

Advancement in science and technology are encouraging people to revisit the past in hopes of answering questions that have remained unanswered. Techniques from the 20th century are applied to cases dating back as far as ancient times.

Investigators are always on the cutting edge of new forensic techniques that can help them solve cases more accurately. Advanced techniques allow crime solving to take on a new dimension, providing safer and more efficient ways to capture criminals.

Insurance torchings, mob burnouts and arson murders: these crimes are designed to take all clues with them. But a case can be built from ashes. Arson investigators do everything from gathering physical evidence to mounting undercover operations.