A Tulsa man is gunned down in broad daylight, while in New Orleans a man is shot after a text message lands in the hands of a killer.

Paula digs into the case of a woman shot dead by a road. All police have to go on is a bullet. Is it enough to catch her killer?

A doctor who makes house calls has the bedside manner of a saint for his elderly female patients, but when the family of a deceased patient contests the will the truth is exhumed.

When a sniper randomly guns down students and pedestrians from atop the University of Texas clock tower, police have no plan in place for such an event. There’s pandemonium until two cops and a civilian join forces.

After a night out leaves an innocent man dead, detectives follow up on solid leads that go nowhere. But then they discover a motive they never expected.

A young mum and her six-month baby vanish in a quiet neighbourhood. For investigators and locals, it's the start of a terrifying murder mystery.

When a killer bursts into a Honolulu conference room he leaves behind seven dead in the biggest mass slaying in Hawaiian history.

When the body of 41-year-old Marsha Spicer is discovered in Missouri, police discover her links to an ex-con who had a fantasy to make a snuff film.

When a stray bullet kills a retired preschool teacher, Atlanta detectives need a witness to break the code of silence surrounding the crime.

A woman is abducted from a shop at night. Then, three more women disappear in shocking circumstances. Paula investigates.

Female students are disappearing with alarming frequency from a college town in California. Then mutilated body parts begin to show up. The police investigation stalls, but then they begin receiving calls from the murderer.

At hospitals in New Jersey and Pennsylvania, patients are dying and the rumour is that a serial killer is at work. Computer records lead police to night shift nurse Charles Cullen.

When a shootout in an Atlanta rap studio leaves two men dead, detectives discover a vengeful motive.

A brave woman risks her life to get justice when investigators struggle to crack the case of a teenager killed just steps from her home.

The story of former beauty queen Michele MacNeill, who was found dead in her bathtub amid rumours her doctor husband was having an affair.

Police are alerted when a man dressed as Santa turns up to a family Christmas Eve party carrying a handgun and a gift-wrapped flamethrower.

When exotic dancer Anson 'Buzz' Clinton is found shot to death by the side of the highway, it looks like a drug deal gone bad. But the investigation leads police officers into a tangled murdered plot involving crooked lawyers and a family bent on revenge.

It looked like a typical robbery, but things were far from what they seemed when Navy officer Cory Voss was shot at a cash machine after months at sea.

When David Harmon is bludgeoned to death in his bed, his traumatised wife tells a lurid story of masked burglars, but police start to suspect there is something evil afoot in this conservative religious town.

When 17-year-old Missy Avila is found drowned in a woodland stream, police discover she has been badly beaten and her long hair cut off. The investigation slowly unravels a passionate story of rage, jealousy, and betrayal.

Investigators search for 23-year-old Dalene Carlson after she is reported missing. But then a tractor operator makes a gruesome discovery in a cornfield.

A look at how police tracked down Stephen Port, the East Londoner responsible for murdering at least four men and for committing multiple rapes.

A 26-year-old escort becomes a media sensation when she is charged for trying to hire a hitman to kill her husband and makes headline news.

When the Sachs family is torn apart by a vicious shooting, investigators reveal a surprising list of enemies who had the victims in their sights.

After one of their own is executed in cold blood, New Orleans homicide detectives learn their suspect may have killed before.

Two brutal attacks strike fear into a Colorado city sending police on a desperate hunt for a hammer-wielding madman.

California police investigate the 2010 murder of Julie Kibuishi and the mysterious disappearance of her friend Samuel Herr.

Rosemary and Fred West's children tease each other: disobey mum or dad and you'll end up “under the patio.” A detective overhears this and sends police to the home. They discover a body under the patio and the remains of eight women in the cellar.