Power Plant shooter: After working for 30 years at the same factory, Timothy Hendron snaps and goes on a rampage, hunting down his boss and his co-workers and executing them one by one. (S4 Ep24)
Dallas Cop Killer: Army private Micah Xavier Johnson faces allegations of sexual harassment. His discharge turns him into an assassin bent on shooting police during a protest in Dallas. (S4 Ep23)
Murder of a Finance Minister: When two gunmen execute a Russian banker police wonder if he was involved with the Mafia, but it turns out he was leading the charge to clean up corruption. (S4 Ep22)
Death by Dominatrix: When a brilliant banker is found dead wearing only a bodysuit, authorities spare no expense to find his killer. Did the sexy games go too far or is it murder? (S4 Ep21)
Suffolk Strangler: British fork-lift driver Steve Wright turns the county of Suffolk into the scene of his serial killing spree with the murder of five women working as prostitutes. (S4 Ep26)
Baton Rouge Massacre: Gavin Eugene Long targets police in the line of duty. Six officers are shot and three killed as SWAT teams try to stop him from taking down as many officers as he can. (S4 Ep25)
Power Plant shooter: After working for 30 years at the same factory, Timothy Hendron snaps and goes on a rampage, hunting down his boss and his co-workers and executing them one by one. (S4 Ep24)
Dallas Cop Killer: Army private Micah Xavier Johnson faces allegations of sexual harassment. His discharge turns him into an assassin bent on shooting police during a protest in Dallas. (S4 Ep23)
Murder of a Finance Minister: When two gunmen execute a Russian banker police wonder if he was involved with the Mafia, but it turns out he was leading the charge to clean up corruption. (S4 Ep22)
Death by Dominatrix: When a brilliant banker is found dead wearing only a bodysuit, authorities spare no expense to find his killer. Did the sexy games go too far or is it murder? (S4 Ep21)
British Pub Massacre: An actor is stabbed to death defending his brother. As the investigation unfolds we discover that when a rowdy teen goes looking for a fight, he will usually find one. (S4 Ep20)
Drugging Your Dates: When Lucie Blackman goes missing in Japan, the evidence leads back to a wealthy businessman with an obsession for drugging and raping Western women. (S4 Ep19)
Murder of the Mounties: A mysterious shooter goes on a bloody rampage targeting police officers. Authorities must capture this dangerous criminal before more lives are lost. (S4 Ep18)
Railway Killer: A serial killer rides the rails across the US. But when two Florida teens go missing, can police find them before they cross paths with a killer? (S4 Ep17)
Oklahoma City Bombing: A dark day in American history - the bombing of an Oklahoma City building by Timothy McVeigh. The FBI dig into the dark history of the man who killed 168 people. (S4 Ep16)
On the Hunt For Humans: A killer turns Phoenix, Arizona, into an urban hunting ground. As the bodies pile up, police face the challenge of tracking down not one, but two serial killers. (S4 Ep15)
Ohio Craigslist Killers: Four men looking for work on the internet end up on the business end of a gun. Who are the faceless killers luring victims to their death on social media? (S 4 Ep14)
Self Defence or Murder?: These are the criminals you'd never suspect - smart suits, respectable jobs, but their crimes prove you can never judge a book by its cover. (S4, Ep13)
Revolutionaries and the Rich Girl: These are the criminals you'd never suspect - smart suits, respectable jobs, but their crimes prove you can never judge a book by its cover. (S4, Ep12)
Honeymoon Carjack: These are the criminals you'd never suspect - smart suits, respectable jobs, but their crimes prove you can never judge a book by its cover. (S4, Ep11)
San Francisco Dog Attack: These are the criminals you'd never suspect - smart suits, respectable jobs, but their crimes prove you can never judge a book by its cover. (S4, Ep10)
Ice Pick Killer: These are the criminals you'd never suspect - smart suits, respectable jobs, but their crimes prove you can never judge a book by its cover. (S4, Ep9)
Bomb in a Bali Nightclub: On a warm October night, bomb blasts tear through the tourist district of Kuta on the island of Bali. Who is to blame? (S4, Ep8)
Long Island Railroad Killer: Colin Ferguson walks onto a Long Island Rail Road train and fires at passengers, killing six and wounding 19. His defence at his trial is that he was framed. (S4, Ep6)
Bomb in Madrid: 191 people are killed and more than 1,800 injured in a mass murder in Madrid that becomes the deadliest Islamic attack in Western Europe to date. (S4, Ep5)
Passenger Plane Down: In March 2015, co-pilot Andreas Lubitz crashes a German airliner into the remote French Alps and the flight's data recorder shows he crashed the plane intentionally. (S4, Ep2)
Cop Killer: Ex-policeman Christopher Dorner declares war on law enforcement and goes on a cop killing spree. A cabin standoff leads to a dramatic shootout in which he refuses to surrender. (S4, Ep1)
Suffolk Strangler: British fork-lift driver Steve Wright turns the county of Suffolk into the scene of his serial killing spree with the murder of five women working as prostitutes. (S4 Ep26)
Baton Rouge Massacre: Gavin Eugene Long targets police in the line of duty. Six officers are shot and three killed as SWAT teams try to stop him from taking down as many officers as he can. (S4 Ep25)
Power Plant shooter: After working for 30 years at the same factory, Timothy Hendron snaps and goes on a rampage, hunting down his boss and his co-workers and executing them one by one. (S4 Ep24)
Dallas Cop Killer: Army private Micah Xavier Johnson faces allegations of sexual harassment. His discharge turns him into an assassin bent on shooting police during a protest in Dallas. (S4 Ep23)
Murder of a Finance Minister: When two gunmen execute a Russian banker police wonder if he was involved with the Mafia, but it turns out he was leading the charge to clean up corruption. (S4 Ep22)
Death by Dominatrix: When a brilliant banker is found dead wearing only a bodysuit, authorities spare no expense to find his killer. Did the sexy games go too far or is it murder? (S4 Ep21)
British Pub Massacre: An actor is stabbed to death defending his brother. As the investigation unfolds we discover that when a rowdy teen goes looking for a fight, he will usually find one. (S4 Ep20)
Drugging Your Dates: When Lucie Blackman goes missing in Japan, the evidence leads back to a wealthy businessman with an obsession for drugging and raping Western women. (S4 Ep19)
Passenger Plane Down: In March 2015, co-pilot Andreas Lubitz crashes a German airliner into the remote French Alps and the flight's data recorder shows he crashed the plane intentionally. (S4, Ep2)
Cop Killer: Ex-policeman Christopher Dorner declares war on law enforcement and goes on a cop killing spree. A cabin standoff leads to a dramatic shootout in which he refuses to surrender. (S4, Ep1)
Murder of the Mounties: A mysterious shooter goes on a bloody rampage targeting police officers. Authorities must capture this dangerous criminal before more lives are lost. (S4 Ep18)
Railway Killer: A serial killer rides the rails across the US. But when two Florida teens go missing, can police find them before they cross paths with a killer? (S4 Ep17)
Oklahoma City Bombing: A dark day in American history - the bombing of an Oklahoma City building by Timothy McVeigh. The FBI dig into the dark history of the man who killed 168 people. (S4 Ep16)
On the Hunt For Humans: A killer turns Phoenix, Arizona, into an urban hunting ground. As the bodies pile up, police face the challenge of tracking down not one, but two serial killers. (S4 Ep15)
Self Defence or Murder?: These are the criminals you'd never suspect - smart suits, respectable jobs, but their crimes prove you can never judge a book by its cover. (S4, Ep13)
Revolutionaries and the Rich Girl: These are the criminals you'd never suspect - smart suits, respectable jobs, but their crimes prove you can never judge a book by its cover. (S4, Ep12)
Honeymoon Carjack: These are the criminals you'd never suspect - smart suits, respectable jobs, but their crimes prove you can never judge a book by its cover. (S4, Ep11)
San Francisco Dog Attack: These are the criminals you'd never suspect - smart suits, respectable jobs, but their crimes prove you can never judge a book by its cover. (S4, Ep10)
Ice Pick Killer: These are the criminals you'd never suspect - smart suits, respectable jobs, but their crimes prove you can never judge a book by its cover. (S4, Ep9)
Bomb in a Bali Nightclub: On a warm October night, bomb blasts tear through the tourist district of Kuta on the island of Bali. Who is to blame? (S4, Ep8)
Assassination Of Anna: Anna Politkovskaya is a Russian journalist and human rights activist. Shot dead, reports indicate a contract killing. Who is behind this very public assassination? (S4, Ep7)
Long Island Railroad Killer: Colin Ferguson walks onto a Long Island Rail Road train and fires at passengers, killing six and wounding 19. His defence at his trial is that he was framed. (S4, Ep6)
Bomb in Madrid: 191 people are killed and more than 1,800 injured in a mass murder in Madrid that becomes the deadliest Islamic attack in Western Europe to date. (S4, Ep5)