True-crime author Michael Arntfield talks about homicide detective Pat Postiglione, who headed up Nashville's cold-case Murder Squad and solved dozens of unsolved murders, and how the country-music mecca became a murder hub.

On September 29, 1982, and in the few days that followed, seven people in the Chicago area died in Tylenol-related poisonings. The capsules were all laced with cyanide. The killer or killers have never been found.

Read an excerpt from Michael Arntfield's true-crime book, 'Monster City,' about serial killer Tom Steeples, a computer store owner who found two of his victims, a newly married couple, at a dive bar's amateur showcase.

With the national homicide-clearance rate below 60 percent, the odds are good that eventually a detective—even an excellent one—will run into a dead end: The case that goes cold, that leaves a family grieving without justice and a detective grasping for answers, even after retirement.

Gary Leon Ridgway, who raped and murdered more than 49 women, was obsessed with deviant sex and visiting prostitutes. This, combined with his aggression and violence, were significant driving forces behind his murderous actions, says Mary Ellen O'Toole, a retired FBI senior profiler who interviewed Ridgway.

Move over fingerprints—an exciting new field of forensics has emerged: DNA phenotyping, where investigators interpret DNA left behind at a crime scene to make predictions about what the perpetrator might look like. We spoke with Ellen Greytak, a bioinformatics expert, to learn more about the use and limitations of this new science.

Tricia Griffith, who runs the web forum Websleuths, talks to A&E True Crime about her close encounter with Ted Bundy, how the online community dug into the Casey Anthony case and why she believes police should let amateur detectives help investigations.

Rebecca Morris, a New York Times bestselling author and high-school classmate of murder victim Dick Kitchel, returns to her hometown of Corvallis, Oregon to explore how the cold case murder changed the town and the lives of Kitchel's friends.

In 1991, four teenage girls were brutally murdered in a yogurt shop in Austin, Texas. The killers have never been caught and the crime has never been solved.

Why do so many killers—Jeffrey Dahmer, Ted Bundy and David Berkowitz to name a few—abuse animals before targeting people? An expert provides insights on how the two behaviors are linked.