In 2016, in the shadow of Manhattan's skyline, a killer stalks women undetected. But a quick-thinking friend, a final phone call, and a social media chat log point to a serial killer who may never have been caught.

In 2016, in the shadow of Manhattan's skyline, a killer stalks women undetected. But a quick-thinking friend, a final phone call, and a social media chat log point to a serial killer who may never have been caught.

In rural Missouri, reptile breeder Ben Renick is found dead–surrounded by his collection of exotic snakes. Investigators have to wade through dozens of potential suspects before finding a text chain from Ben that leads to a true snake.

In rural Missouri, reptile breeder Ben Renick is found dead–surrounded by his collection of exotic snakes. Investigators have to wade through dozens of potential suspects before finding a text chain from Ben that leads to a true snake.

When 32-year-old John Ray is murdered in his Atlanta home, investigators are stumped. For seven years, his case goes unsolved until cold case detectives take another look at the evidence and find that John had identified his killer all along.

When 32-year-old John Ray is murdered in his Atlanta home, investigators are stumped. For seven years, his case goes unsolved until cold case detectives take another look at the evidence and find that John had identified his killer all along.

Armada, Michigan could be ripped from a Norman Rockwell painting, but the town changes forever when April Millsap's body is found. Police search for the teen's missing phone and discover a fitness app could hold the key to finding her killer.

Armada, Michigan could be ripped from a Norman Rockwell painting, but the town changes forever when April Millsap's body is found. Police search for the teen's missing phone and discover a fitness app could hold the key to finding her killer.

In the winter of 2013, 14-year-old Shaniesha Forbes never made it home after school. Her charred remains turn up on a Brooklyn beach days later, but this teen leaves behind a mountain of digital evidence for the NYPD to sift through to find her murderer.

In the winter of 2013, 14-year-old Shaniesha Forbes never made it home after school. Her charred remains turn up on a Brooklyn beach days later, but this teen leaves behind a mountain of digital evidence for the NYPD to sift through to find her murderer.

Shockwaves rip through a college campus in Missouri when 21-year-old Jesse Valencia is found, his throat slashed. With a litany of suspects – and a secret revealed by Jesse – investigators must untangle a web of lies to uncover an unlikely killer.

Shockwaves rip through a college campus in Missouri when 21-year-old Jesse Valencia is found, his throat slashed. With a litany of suspects – and a secret revealed by Jesse – investigators must untangle a web of lies to uncover an unlikely killer.

In 2012, Brandy Rosine drives an hour into Pennsylvania, but as night falls, the college student stops answering her family's calls. It's up to her mom to follow a trail of digital breadcrumbs Brandy left behind to find her daughter's killers.

In 2012, Brandy Rosine drives an hour into Pennsylvania, but as night falls, the college student stops answering her family's calls. It's up to her mom to follow a trail of digital breadcrumbs Brandy left behind to find her daughter's killers.

When 14-year-old Candice Parchment goes missing, the police write her off as a runaway. Months later, her body is found blocks from her home. Investigators are stumped until Candice's own writing helps uncover the horrifying truth behind her murder.

When 14-year-old Candice Parchment goes missing, the police write her off as a runaway. Months later, her body is found blocks from her home. Investigators are stumped until Candice's own writing helps uncover the horrifying truth behind her murder.