In 2004, Mary Ann Clibbery was found brutally murdered in her Illinois business and investigators had to determine if this was a robbery gone wrong or a calculated murder. The evidence at the scene told police what happened and they got a huge break when evidence from the murder was found on top of a nearby frozen river.

In 2006, Texas real estate agent Sarah Anne Walker was found brutally murdered in a model home. Weeks later, a witness came forward who may have seen the killer and police used forensic hypnosis to help him recall every detail of the man's appearance. His description was used to create a composite sketch, which police used to draw the killer out of hiding.

In 2003, St. Cloud teenager Jason MacLennan returned home after a night out with friends and discovered his father Ken's body lying in a pool of blood. There were shoe impressions outside in the new-fallen snow; because the victim's wallet and watch were missing, the motive may have been robbery. But before making that determination, police needed to find out who had the most to gain from his death.

In 2006, Nevada politician Kathy Augustine died mysteriously during a hard-fought re-election campaign and the medical examiner could neither isolate the cause of death, nor explain the tiny puncture wounds discovered during the autopsy. Upon deeper analysis, investigators focus on her husband Chaz Higgs, a critical care nurse who had ready access to succinylcholine.

In 1996, Virginia Beach police arrive at the Makdessi apartment to find Elise Makdessi and her lover Quincy Brown dead. Elise's husband Eddie had reported that he killed Quincy Brown in self defense after Brown had murdered Elise. Eddie gave the police a videotape Elise had made a week before, alleging that she had been the victim of sexual harassment and assault while in the Navy. Investigators found evidence that her allegations may have been part of an elaborate scheme for financial gain. Hoping to separate fact from fiction, they turned to forensic science.

In 1999, Patrick McRae was found dead in his Des Moines home and the crime scene was awash with blood. Analysis showed it had come from two people, one of whom was female. The male DNA was McRae's, which meant the killer was a woman. Leads dried up and the case went cold until a suspect arrested for drug possession offered police a deal, and told a bizarre tale of an exotic dancer named Andrea Morris who listened to the voices in her head.

In 2000, the body of exotic dancer Rachel Siani was found beneath a New Jersey bridge and investigators wondered if she had committed suicide. Evidence at the scene proved not only that she'd been carried to the bridge and thrown over the side, but also that she was alive when she fell. Police look at customers at the gentlemen's club and co-workers who had vendettas against the victim.

In 2000, construction manager Darrell North was found dead in his work trailer in Ft. Worth, Texas. When investigators arrived, they found that he had been stabbed 46 times, described as overkill and indicating a personal relationship between the victim and the attacker. Police hoped that, during the struggle, the killer had left some of his own blood and his DNA behind. Their challenge was to find it. Forensic science points to an unlikely suspect.

In 2000, Judy Southern arrived home from work and was shot by a gunman waiting within. Her husband Allen arrived shortly afterwards, called 911 to report his wife had been shot and drove her to the hospital. She died on arrival and the investigation focused on her husband Allen, but forensic analysis and a suicide note found at the scene pointed to the killer.

In 1986, Gary Dale Larson was stabbed to death in his Edmond, OK, home and then the killer sexually assaulted Larson's girlfriend Janet Haynes. Hayne's story seemed farfetched: The perpetrator was wearing only underwear and gloves broke into the house, stabbed Larson to death, then raped and terrorized her for hours afterwards. But, the evidence at the scene supported her story, and investigators turned for help to the FBI and their criminal profilers.

In 1991, Dorothy Donovan was murdered in her Dover, DE home and police are skeptical when her son Charles Holden stated that she was murdered by a hitchhiker he had picked up. Their suspicions were heightened when he refused to take a polygraph test and they turned to forensic science. Would the blood and fingerprint evidence at the crime scene support Charles' story or prove his guilt?

In 2001, Ginger Hayes and her infant son Nicholas were abducted during a carjacking and the crime had been reported by a witness within minutes of occurrence. 45 minutes after the kidnapping, When Ginger and Nicholas were found 50 miles away, Ginger had been beaten to death, but Nicholas was still alive. Further analysis of Ginger's car and evidence at the scene where Ginger was found both led to her killer.

In the early hours of a morning just before Christmas, a college co-ed was abducted from the parking lot of her apartment. Her body was found later that day; she'd been sexually assaulted and then shot at point blank range. Eight long years passed and then a pair of running shoes and a cell phone breathed new life into a very cold case.

A young woman is found dead in her apartment. There's little evidence at the scene, leads don't pan out and the case turns cold... until police discover a link between their prime suspect and an unsolved murder committed six years earlier in different state.

A serial rapist is on the loose in a Texas town. No one knew where he'd strike next, but the audacity of his attacks and the escalation of violence against his victims made finding him imperative.

The victim has been stabbed more than thirty times, and the crime scene is awash with her blood. Near her head, police discover a distinctive button with strands of thread still attached. If they can find the owner of the shirt the button came from, they'll also find the killer.

A young woman attends evening church services... then disappears. When her abandoned car is found, the tank is empty and a gas can she kept in her trunk for emergencies is missing. Eyewitnesses place her at a nearby gas station, getting into a van, but their descriptions of the vehicle don't match. Three days later when her body is discovered, the search for the driver of that van intensifies.

When a nine-year-old girl goes missing, police and volunteers spend weeks searching for her. A psychic's vision leads to a field where her body is discovered, along with what investigators hope is enough evidence to help them to also find her killer.

Digital enhancement of security camera video shows that what appears to be a casual encounter is actually a forced abduction, leading to murder. The perpetrator's M.O. is remarkably similar to another murder which occurred five months earlier, 15 miles away. When investigators learn the crimes might not be isolated or random, they also realize a serial killer may be on the loose.

The woman had been sexually assaulted, stabbed repeatedly, and left for dead. She survived, and gave police a detailed description of her attacker. When someone who fit that description practically turned himself in, police were sure they had their man... until the DNA evidence proved them wrong.

The victim was a self-made man who never minced words. Perhaps he was murdered by a disgruntled client or employee. Perhaps the racy photos in his safe held the clue to solving the crime. Or perhaps with the help of the IRS, investigators could follow the money and find the killer.

A family vacation turns into a nightmare when the wife is found face-down in the lake. There are no witnesses and little conclusive evidence to help police determine if they're dealing with a suicide, an accident, or something more sinister... until a forensic pathologist uses a groundbreaking technique to discover the truth.

The woman in the back of the truck was flailing her arms, screaming. They thought she was doing something dangerous for the fun of it. But when they found a jacket near a pool of blood, they knew what they'd seen wasn't a joy ride; it was an abduction.

When court clerk Peter Porco doesn't report to his work in November 2004, a courts officer is ordered to the Porcos' family home in Bethlehem, NY. Inside the home, he finds murdered Peter Porco and his barely alive wife Joan who had both been savagely attacked with a fireman's axe. Eventually, a DNA sample may lead to the killer.

Detectives think they've solved a murder when they find the weapon and victim's blood in a man's flat, but the evidence may have been planted.

A serial bomber was on the loose in Illinois. Two churches had been bombed and one person was killed. Investigators had to capture the criminal before he struck again and they hoped to catch him by following a thin copper wire.

There was no clear reason for a young, healthy college student to be dead. But when the medical examiner discovered the tiniest of clues during the autopsy, investigators were able to uncover the mystery filled with betrayal and revenge.

The victim had been stabbed more than a hundred times, leaving her bedroom soaked with blood. Even though her body was positioned in a suggestive way, she hadn't been sexually attacked. Was this a sex crime, or was it a random act of violence?

On Christmas eve 2005, the corpse of a black male is found burning near Baltimore. He's eventually identified as 26-year-old Wesley Person. Distinctive building materials from the 1930s found near the body play a crucial role in solving this case.

Doctors don't know why a young scientist is gravely ill. When tests finally reveal the cause, it's too late to save him. Police hope that lab analysis of his hair, showing when attempts were made on his life and what was used, will lead to the killer.

A bullet-riddled car, a missing driver, and no witnesses. Was this an ambush or a random attack? Had the victim been abducted or was she dead? The answers lay in a unique clue so tiny it was measured in millionths of a meter.

Even though their daughter had run away before, she'd always come back. Her parents were sure this time would be no different, but they were wrong. Workers discovered the teen's half-naked body on the side of the road; her throat had been slit. Police hoped the single foreign hair found in a defensive wound on her thumb would lead them to the killer.

In little more than a month, two women who lived in the same apartment complex were brutally murdered. The similarities of the crime scenes led police to conclude they were dealing with a serial killer who harbored an intense hatred of women... and they had to find him before he struck again.

When a college co-ed vanished without a trace, her fellow students were concerned about her safety and their own. Weeks later, the body of an unknown female was discovered 700 miles away in the ashes of a barn fire, and an alert police officer realized the two crimes might be connected.

The victim was well liked and successful, which made the brutality of the crime even harder to understand. In the final moments of her life, she'd written a name on the wall, presumably that of the killer – in her own blood. But this wasn't an open and shut case and, in order to solve it, investigators would have to read between the lines.

An assistant manager of a Florida steakhouse is stabbed to death. It appears to be a robbery gone wrong, but a bloody fingerprint reveals that he knew his killer.

In 1985, Julie Estes, then 21, was abducted from her late-night job at the Southside convenience store. Her body was found the next day, she had been raped and strangled. Her murder went unsolved until 2003 when it was reopened by the new cold case squad at the Jacksonville Sheriff's Office, who look to DNA evidence to try to nail the killer.

In April 2002, a wild fire in a secluded parking lot leads police to discover the dreadful homicide of David Nixon, with the suspect's image caught by security cameras.

Respected surgeon Brian Stidham was stabbed to death in the parking lot next to his office. The most likely suspect is seen having dinner in a restaurant at the time of the murder. But a cryptic conversation leads police to believe that, while the suspect may not have wielded the knife, he could very well have hired the man who did.

In 2007, Brian & Beverly Mauck were found dead in their Graham, WA home. The killer obviously spent a great deal of time at the scene, wiping away his fingerprints and obscuring shoe impressions he’d tracked through blood trails on the floor. But in the process, he created new evidence which was just as incriminating.

Terrified, the young girl hid in her bedroom while her mother, Crystal Perry, was attacked and stabbed to death in her home in Bridgton, ME, on May 12, 1994. Investigators had a wealth of evidence: shoe impressions, distinctive blood drops, and the killer’s DNA. What they didn’t have was a basis for comparison.

On December 10, 2003, a gunman opened fire as a family of four entered their home, killing two and wounding the others. He’d pulled open a few drawers to make it look like a robbery, but the scene was clearly staged. When police pieced together the clues, they discovered an unlikely suspect and a carefully orchestrated plot.

It was classic “overkill.” Barbara Mullenix, found floating in the harbor of an upscale yacht club in Newport Bay on September 13, 2006, had been stabbed more than 50 times. Her ex-husband and daughter are missing, and investigators turn to forensic science to determine if they’re searching for victims... or perpetrators.

On May 20, 2001, 20-year-old state park employee Carrie Nelson was beaten to death in the park office while working alone in the middle of the afternoon. There’s a wealth of evidence at the scene, but it doesn’t implicate the prime suspect, it clears him. Six years -- and 600 leads -- later, advances in DNA technology enable investigators to identify and convict the killer.

Foul play is suspected when Fort Worth factory worker Glenda Furch disappears in September 2007 after completing her shift. Evidence suggested she had been bound, sexually assaulted and murdered. Afterwards, the killer spent hours at the crime scene, wiping away his fingerprints and disposing of everything which might incriminate him, including her body. Police now face a daunting task: They not only have to find the killer, they also have to find the body of the victim.

Joshua Ford and Martha Crutchley spent Memorial Day weekend at the beach, and then they simply vanished. A week later, police would get an unexpected lead from a robbery in progress, and the evidence they found helped solve a crime of unparalleled violence and brutality.

Whoever stabbed a young Texas mother to death had also savagely beaten her 4-year-old daughter. Police had a suspect, but not enough evidence to tie him to the crimes. It would take 15 years and advances in DNA technology to bring the killer to justice.

In 1995, Palm Beach waitress Denise O'Neill is abducted and murdered. Her neighbor, Luis Caballero, arouses suspicions by his odd behaviour towards TV crews covering the crime.

In 2007, Shamaia Smith disappeared from the strip club she worked at in East Hartford, CT. Police look at various customers of the strip club, but focus on local businessman Kenneth Otto when there were inconsistencies with his story. Upon search of Otto's rural property, cadaver dogs find something in a fire pit.