TV Guide Investigation Discovery Sunday

An unhappy, young, married mother takes to Tinder under a pseudonym and embarks on a steamy affair, but then her identity surfaces and her lies are exposed.

A new girl arrives in town and it causes heads to turn, including the local heartthrob and together they embark on an affair that leads to mayhem and murder.

A love triangle unfolds at a medieval historical reenactment group and with weddings, miscarriages and broken promises, things soon turn messy.

A bitter rivalry between two sisters gets out of hand when the family moves to Las Vegas, which leads their dispute to transition among the next generation.

Jealousy, greed and a hunger for power threatens the luxurious lifestyle of a Los Angeles family, which ultimately leads to a double murder.

Dana Satterfield, a 27-year-old mother, is found raped and strangled in her South Carolina hair salon, and her killer is still on the loose.

Police investigate when a married couple is shot inside of their home, as the husband survives the shooting but the wife later dies at the hospital.

After Anthony Anastasi was found dead in his home, his wife Ann said that it was suicide, but then Jacqueline Riggs was found stabbed to death in the basement.

After the shooting of Sharon Causse in an apparent home invasion, detectives question who committed the crime, her handyman or her husband.

Thomas Randolph has a dark past: he's been married six times and four of his wives are dead; Thomas Randolph's history is revealed in the lead-up to his trial.

Over 8 years, the infamous Black Widower Thomas Randolph stands trial for the murder of his wife and her handyman; the victims' families want justice served.

After years apart, Jamie-Lee Arrow reunites with her father, Isakin Drabbad, the Skara Cannibal, to confront him over his girlfriend's murder.

After years apart, Jamie-Lee Arrow reunites with her father, Isakin Drabbad, the Skara Cannibal, to confront him over his girlfriend's murder.

Old friends Louis and Tonya fall for each other over time and marry, but Louis heads down a dark and violent path, ending in a brutal murder.

Kristin and her brother were raised in foster care, but as he grew, he turned into a violent criminal and then committed brutal murders.

A vehicle mows down a 75-year-old military veteran on a country road in an apparent hit-and-run, but a young man confesses to the heinous crime.

When a young mother goes missing, her husband joins the search, but then the police discover her dismembered body in a stack of bins.

A killer guns down a 46-year-old woman and detectives discover that a fleeing sheriff's deputy is the assailant and he is an unrepentant psychopath.

After the shooting deaths of a family in their suburban Baltimore home, investigators realize it's not a robbery gone wrong, but rather an execution.

An apartment fire reveals dead bodies and detectives find a psychopath who appears polite and gentle, then later as a pawn of imagined demons.

Police first arrest a man for discharging a firearm and discover dead bodies inside his apartment, and detectives try to make sense of the bloody crime scene.

Experts look at a subset of psychopaths who are motivated by their heightened sexual urges and fantasies, enacting sexual violence toward their victims.

Cathy Mills' marriage to Robert Walden turns into a nightmare, and she realizes that only she knows the identity of the monster authorities are hunting.

Teresa Holman wishes that her father, Freddie Bowen, would die for the things he does to his family, but when she gets a chance, it has consequences.

A young man misunderstands his arresting officers, then another DUI suspect tries to prove his sobriety by performing a backflip; a man steals an officer's gun.

Tawnee Baird and Victoria Mendoza fall in love when they're teens, but when passion turns to rage, only one young woman will make it out alive.

Teresa Holman wishes that her father, Freddie Bowen, would die for the things he does to his family, but when she gets a chance, it has consequences.

A young man misunderstands his arresting officers, then another DUI suspect tries to prove his sobriety by performing a backflip; a man steals an officer's gun.

Tawnee Baird and Victoria Mendoza fall in love when they're teens, but when passion turns to rage, only one young woman will make it out alive.

Cathy Mills' marriage to Robert Walden turns into a nightmare, and she realizes that only she knows the identity of the monster authorities are hunting.

79-year-old Lila Warwick was a loving and hands-on grandmother of eight, whose door was always open, until she opened her door to the wrong people in July 2013.

When 22-year-old LeAnne Martinez fails to pick up her daughter, her family worries, but what they find inside her mobile home will leave them forever scarred.