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.

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.

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.

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.

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.

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 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.

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.

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 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 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 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.

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.

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.

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.

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 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.

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 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?

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.

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.

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.

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.

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.