Devoted father and aspiring boat captain Tray Phelps takes his last breath, murdered just steps from his front door; with no immediate leads, it's up to Missouri investigators to find the murderous manipulator at the heart of a sordid family plot. [also shown as S6:E19]

As detectives reconstruct a single mom's final 24 hours, their suspicions turn to her fiancé, a creepy co-worker, and a violent ex-boyfriend. Ultimately, investigators discover a disturbing pattern of attacks -- and a predator with the master key. [also shown as S6:E23]

After Michigan detectives find a popular hairstylist stabbed to death, their suspects include the victim's landlord, her married lover and an aggressive ex-boyfriend; an unexpected call ultimately leads police in the right direction. [also shown as S6:E24]

Deputies in Tennessee find a beloved Memphis-area basketball coach murdered in his home. As investigators dig deeper into his closest relationships, they gradually unravel a homicidal web of deception, lies, and family honor. [also shown as S6:E25]

After Santa Barbara Police find a Ph.D. student shot dead on his doorstep, California investigators unravel a cold-blooded family plot that hinges on a single strand of DNA. [also shown as S6:E26]

On Easter Sunday in Agawam, Massachussetts, police find the body of a 24-year-old woman. With DNA in its infancy, it will take 25 years before a determined DA, advances in DNA technology, and a suspect’s plea can bring the case to its shocking conclusion. [also shown as S6:E27]

When a charming 33-year-old is gunned down outside his home, detectives must comb over every detail of his personal life, professional dealings, and extracurricular activities to figure out who could commit such a brutal crime, and why.

After being stabbed at his Marietta, Georgia, home, beloved son Mitchell Jones dies at the hospital. Mitchell is a popular gay man, so police have several potential suspects. It isn't until they employ a new tracking tool that the case breaks wide open.

A killer guarantees that a popular square dancer will do-si-do no more.

A concerned husband fails to get in touch with his wife after an alarm is tripped at their house, so he calls on the police to check it out. Upon arrival, they find his wife dead and try to connect the dots between an earlier burglary and a love triangle.

A 45-year-old yoga instructor is found gunned down on his front porch on a hot September morning in Tucson. With evidence of a burglary, detectives wonder if the victim interrupted the crime. The case proves much more complex when a witness steps forward.

When a small-town Michigan couple is gunned down in their own home, footprints in the snow and loose lips will lead police to their killer.

A popular college student is found stabbed to death in her apartment the day after Thanksgiving. Detectives in Jacksonville Beach must piece together her last known movements to pinpoint the time of the murder, and then they must find her brutal killer.

Mary loves her 40-year marriage and her thriving chiropractic practice in Whitesboro, New York. Then, she falls ill at work and dies two days later. An autopsy points to poisoning, and a mysterious letter implicates someone close to her.

When a body found dumped in a gritty Brooklyn neighborhood is later identified as criminal justice student Imette St. Guillen, detectives must retrace her final hours at a Manhattan bar to catch her killer.

After his contentious divorce, Josh Niles finds love with Amber Washburn. Josh’s kids join their new family in Sodus, New York, and life seems like a fairytale until a determined gunman shatters their happily ever after.

A 30-year-old woman is reported missing by her concerned husband after she fails to report to work. When her abandoned car is found, traces of blood in the trunk indicate more than just a disappearance - it's clear she has been murdered.

A former marine's death reveals a string of angry coworkers and irate exes.

A popular Wisconsin funeral director and his intern are murdered in cold blood. The case stalls for two years before a criminal profiler takes a fresh look and sees only one viable suspect -- someone the police never considered.

Gary and Jan Tyrrell are avid collectors of gold and silver coins and artifacts. Then they turn up dead, and investigators must find out exactly who knew about their expensive hobby - and who would be willing to kill for it.

In Tulsa, Oklahoma, taxi driver Rafael Hernandez's community reveres him as a caring and generous entrepreneur. Then, police pull his cab from a local river with Rafael inside, and the race is on to find his killers before they strike again.

Retired mortgage broker Alan Helmick’s blissful life comes to a violent end while enjoying a cup of coffee at his country home in Colorado. He has no known enemies, but when police find a gun, it’s clear someone close to Alan is an expert in murder.

High school Freshman Tina Faelz ditches detention and heads for home - but someone murders her along the way. Suspects are plentiful, including a known sex offender, but decades pass before two determined detectives finally deliver justice for Tina.

Snowplow King Randy Scheffield is found shot dead in his bed by his wife on the first snowy day of the season, and Ohio detectives look into Randy's business to establish a motive.

A two-bit Florida criminal is arrested while driving a stolen convertible that has blood in the backseat, and its owner, a 49-year-old hotelier named Sabine Musil-Buehler, is reported missing; the case expands to include a possible homicide