Often, the witnesses of a crime are also the main suspects. They’re able to manipulate the truth to throw off the authorities. When a murder is committed and deceit clouds the evidence, investigators turn to forensics to uncover the truth.

A simple clue can provide the missing link by placing a suspect at the scene of the crime. Dirt left on shoes, tires or clothes can pinpoint where the crime occurred. It takes the skilled eye of a forensic investigator to follow the trail.

Approximately 1.8 million Americans are reported missing each year. Some are runaways who eventually find their way home but others simply disappear without a trace. When foul play is suspected, investigators turn to forensics to find the missing.

Some people don’t care who they kill; they just want to hurt innocents. Bombers, snipers and spree killers: these murderers are the hardest to catch because they have no connection to their victims, people in the wrong place at the wrong time.

Sometimes blood relations lead to bloodshed. When money is the motive, murder can rip at the very foundation of family and marriage. When homicide becomes a family affair, investigators must turn to forensics to shed light on these crimes.

Even the most puzzling cases can be solved with the tiniest of residue left behind at the crime scene. Trace evidence and paint analysis can be used to track down a serial killer or dog hair can be used to link separate murders to a single suspect.

Poison is an almost invisible form of death and is often interpreted as a heart attack or underlying health issue. But when foul play is suspected, toxicologists must look for hidden clues in blood and tissue to bring these murders to light.

Some people do get away with murder, at least for a while. Thrilled by their success, they tend to kill again and again. But with each crime they leave behind more clues for investigators. In this episode, two serial killers are profiled.

At the scene of a murder, sometimes the only clues to the killer come from the victim. Forensic anthropologists use skeletal remains to decipher the clues written in the bones to bring the murderers to justice.

Time of death is an important consideration in an investigation but when a killer destroys the body, even the best medical examiner would be at a loss about how to calculate death's time frame. Forensics has its own techniques for solving these crimes.

Drowning deaths often look like accidents and over time water can destroy the few clues the killer may have left behind. Investigators must turn to forensic science to solve homicides in which the victims were found in bodies of water.

A dog can be a dead man’s best friend. Some dogs have been trained by law enforcement to sniff out corpses, drugs, explosives and missing persons. Even with advances in science, a dog’s nose is often first to find fundamental clues.