For six years, a serial killer prowled the streets of New York City. He wrote letters to police and The New York Post, indicating he would kill twelve people, one for each astrological sign.

A woman is shot to death in her store just one day before she is to testify against the man accused of robbing her. The robber becomes the prime suspect, but he has a solid alibi: a time-stamped videotape of his activities on the day of the murder.

In 1993, the state of Florida was known for more than just Disney World. Worldwide attention focused on a rash of robberies which targeted tourists. Some vacationers were killed in these attacks, but some fought and survived, despite severe injuries.

At a murder scene, investigators find a shoe-print, several foreign hairs, and unknown fingerprints. But they believe the most telling piece of evidence is the bite mark on the victim's chest.

In 1962, the people of the small town of Hanford, CA lost their sense of peace when one of their own, 15-year-old Marlene Miller, was murdered. Booker T. Hillery was convicted and after countless appeals, Hillery received a re-trial in 1983. Forensic scientists had to use new knowledge of microscopic evidence to be able to place Hillery at the scene.

A 34-year-old nurse experiences a variety of flu-like symptoms. None of her doctors are able to discover the cause, until she visits the gynecologist for a routine check-up. Then she learns it's something far worse than the flu.

A man tells police he shot an intruder who had attacked and murdered his wife. The husband paints a tragic picture and is dubbed a hero. Four years later, forensic evidence leads police to re-examine the motives of this so-called hero.

Time of death becomes pivotal after a pregnant woman is found murdered in her air-conditioned bedroom. A striking similarity between her death and an HBO movie gives examiners the clues they need to thaw out the alibi of a cold-blooded killer.

Police were puzzled by an obscure print found at a crime scene where one man had been killed and two teenage girls were seriously injured. Neither of the girls could identify their attacker. But one simple clue helped track the footsteps of a killer.

A mother of two vanishes after a shopping trip. Her body is discovered a month later. Witnesses say they saw the victim being forced into a car by an unknown person.

A young TV news producer is raped and murdered in her apartment. Police identify two suspects, but both are cleared of any wrongdoing. The case stalls for more than a year, and then investigators turn to the Commonwealth of Virginia's DNA Databank.

A woman is found dead in a ravine, but crucial crime scene evidence had been washed away by severe thunderstorms. Twice, the trail turned cold. Almost 20 years later, an old hat and a chip of stainless steel brought the killer to justice.

Two different men called police to report the same murder. Apparently, neither one knew that the other had called. The investigation uncovered even more unusual circumstances.

The body of a wealthy American businessman was found in his rental car. Teeth and bone fragments were the only remains. When the victim's wife files an insurance claim for $7 million, investigators seek the help of a renowned forensic anthropologist.

When teenager Rosemary Anderson is found dead on the side of the road, her boyfriend eventually confesses to her murder, but in a strange twist, so does another man – serial killer, Eric Edgar Cooke. It would take the passage of another forty years, an author, and an expert in the field of pedestrian accident reconstruction to determine who was telling the truth. [also marked as S8:E26]

In 1999, a 12-year-old was found murdered in her home and it changed the feeling of security residents had in the small town of Waseca, Minnesota. Despite a meticulous search of the home and an exhaustive investigation, police had no suspects.

A woman's death in Pennsylvania triggers a homicide investigation into another woman's death in North Carolina. The similarities in the cases were striking, and examiners must determine if the suspect's story about accidental drowning is all wet.

When an 11-year-old girl disappeared from a small town in a remote area of Alaska, investigators wondered if she'd been attacked by a bear or become lost in the dense woods. It turned out neither was true.

Just weeks before a witness is to testify against the man accused of sexually assaulting her, she is murdered in the front yard of her own home. Investigators immediately suspect her attacker, but they don't have enough evidence to prove his guilt.

A healthy young man dies mysteriously in his sleep. There are no signs of trauma or injury, but toxicology tests reveal a lethal dose of lidocaine in his blood. Investigators find a suicide note, and presume he killed himself until a forensic linguist examines the note and determines that what the victim said is less important than how he said it.

In the summer of 1986, Kathleen Lipscomb's body was found on a deserted road outside of San Antonio. Months passed, then years, and the crime was never solved. Then Kathleen's family hired a private investigator, who discovered her diary.

A retired police officer is discovered in his bed, dead of a single gunshot wound to the head. His wife first says the motive was robbery; then she tells police he committed suicide. It would take careful examination of the evidence at the crime scene, the tape from a bank surveillance camera, and forensic textbooks found in the victim's home to write the final chapter of this real-life whodunit. [also marked as S8:E19]

A sixteen-year-old girl is killed in her own home by her mother and father. Her parents said they acted in self-defense, but the forensic evidence indicates otherwise. Definitive proof would come from an unlikely source: a recording made by an FBI electronic surveillance device. [also marked as S8:E28]

A police officer accused of killing his estranged wife insists she committed suicide. Investigators say it was murder – that it was physically impossible for the woman to have shot herself. The crime scene evidence is interpreted differently by the defense and prosecution, and the jury must decide if the victim's death was suicide or cold-blooded murder.

When Firefighters found an entire family dead, inside their home, it looked like a murder-suicide, but there were several inconsistent clues in the rubble. Could ballistics, a time card, and some secret audiotapes unravel the mystery?