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The investigations of two seemingly random deaths in Seattle lead the authorities to a connection: over-the-counter medication that was tampered with. (Repeat).

An investigation into threatening letters sent to an elementary school teacher leads the police to an unlikely suspect. (Repeat).

On October 15, 1985, two bomb explosions rocked Salt Lake City and resulted in two deaths. A third explosion occurred the next day; this time, the victim was injured but survived. As the investigation progressed, police came to believe the survivor was more than an innocent by-stander. When they turned to forensic science for help, they uncovered an almost unbelievable story of forgery, fraud and

The murder of a 13-year-old boy is investigated, and police find an organism in his lungs that may lead to the cause of death. (Repeat).

Examining the 1993 case of a tainted water supply in Milwaukee that was blamed for the death of 100 people and sickening 400,000 more. Flu-like symptoms were linked to a microbe called cryptospordium. (Repeat).

The deaths of a child and a truck driver in the same hospital on the same day are investigated to see if there is a link between them. (Repeat).

The murders of three women in California are investigated. The killer cut the victims' hair and clothing in a seemingly random pattern. (Repeat).

A forensic anthropologist attempts to identify a human skull found at a Boy Scout camp. (Repeat).

An investigation into a pipe-bomb explosion that killed a young man and seriously injured his mother. (Repeat).

The shooting of a man during a hunting trip is reopened years after the incident, and the victim's hunting partner becomes a suspect. (Repeat).

An 18-year-old girl is abducted while talking on a pay phone. Forensic evidence found on her clothing points police in the direction of a suspect who shockingly confesses that he didn't act alone. (Repeat).

The story is told of kidnapping, ransom, and murder ring in L.A. A pair of retired scientists use sonar equipment to locate the victims at the bottom of a reservoir. (Repeat).

Get the latest news, weather updates, and sports analysis on CNN News Central. Stay informed with all the top stories of the day. (Repeat).

Get the latest news, weather updates, and sports analysis on CNN News Central. Stay informed with all the top stories of the day. (Repeat).

Get the latest news, weather updates, and sports analysis on CNN News Central. Stay informed with all the top stories of the day. (Repeat).

Michael Swango, high school valedictorian, distinguished marine, trusted doctor and serial killer, is spotlighted. For nearly two decades, this physician-turned-murderer left a trail of death and mayhem across two continents. (Repeat).

Dr. Michael Swango took an oath to "do no harm." But he did just the opposite. Suspicious illnesses and deaths followed this once-trusted physician-turned-killer from hospital to hospital for nearly two decades and across two continents. (Repeat).

After a 40-year manhunt, investigators finally unmask California's most prolific serial killer. (Repeat).

The Golden State Killer is identified by law enforcement as Joseph James DeAngelo. (Repeat).

Chronicling the dark life of Robert Hansen, aka The Butcher Baker, one of the most prolific serial killers in Alaska's history. (Repeat).

Recounting the story of a woman who led police to a shocking discovery inside Robert Hansen's home. (Repeat).

A possible case of Munchausen syndrome is investigated after an infant dies of what appears to be toxic levels of antifreeze in his system. (Repeat).

Early one fall morning, Laura Houghteling left her Bethesda home and walked to the station to take a train to work. She was never seen again. A peculiar strand of hair found in Laura's hairbrush enabled investigators to unravel the mystery of her disappearance. (Repeat).

DNA evidence in a 1984 abduction-rape case clears the accused 10 years after the fact. (Repeat).

The 1984 disappearance of a 9-year-old girl in Tucson is investigated. (Repeat).

When a two-year-old boy was rushed to the hospital suffering from brain seizures and breathing difficulties, doctors could not find the cause of his illness. Then the boy's sister provided an important clue, and raised the possibility of a syndrome of which few had ever heard. (Repeat).

Two years pass in the investigation of a missing 18-year-old girl, but the authorities make a breakthrough by re-interviewing her boyfriend and a childhood friend. (Repeat).