TV Guide Investigation Discovery Sunday

An affair ignites between two schoolteachers, with secret trysts occurring throughout the schoolhouse, but then one of them turns out to be married.

A young woman meets a Marine and they fall in love, but underneath this perfect facade hides a dirty double life of drugs and deceit in the desert.

A Michigan couple hire an outsider whose presence changes their marriage forever; a 10-year marriage falls apart when a bored wife pursues an old friend.

A philandering cop avoids an expensive divorce in the worst way possible; a bored wife seeks excitement in a chat room where she meets an Italian stranger.

A relationship at work ignites into a full-blown affair and when the infidelity is exposed, one of them will have more than just their fingers burned.

Deadly women who fulfilled their blood desires with their family are explored.

Murderous women, who are skilled at gaining an advantage, take on the challenge to obtain cash when the stakes are high.

A Navajo woman goes missing after her mother drops her off at her boyfriend's house in Albuquerque, N.M., then the family takes matters into their own hands.

Daniel Robinson arrives at work, then a coworker remarks that he was acting strangely just before taking off in the middle of his shift, never to be seen again.

Alex Gumm's vanishes in Kauai, Hawaii, on February 22, 2018, and his disappearance raises several questions & his friends risk their lives to find the answers.

When a Boston police officer turns up dead in the snow, authorities arrest his girlfriend and then an anonymous tip point to an alleged conspiracy in Canton.

The murder trial of Karen Read begins and jurors hear the testimony from several witnesses at the scene where they found John O'Keefe's body.

As the murder trial continues, more details emerge about allegedly sloppy evidence collection; Karen's team suggests conspiracy and cover-up are at play.

The jury hears shocking testimony about Karen's alleged affair, scandalous texts, mysterious calls and conflicting Google search timestamps.

As the trial winds down, experts attempt to recreate John O'Keefe's death, the defense brings in one final witness and closing arguments grip the nation.

Jeffrey and Jeannine Glanda appear to have it all, but when half of the partnership craves control more than love, it sets in motion a deadly plot.

Roger Harris and his wife Donna have built their dream home in Florida, but just after the birth of their second son, a vile secret threatens their life.

When Wendi Davidson meets Brian Chevalier, it seems to be the perfect remedy for heartbreak, but a shocking revelation will cause history to repeat itself.

What starts as innocent fun night out on the town leads 40-year-old Tammy Gardner down a very dark path, paved with jealousy and deadly rage.

When the father of her children becomes increasingly violent and unpredictable, Brittany Steier must make a decision that will end up costing her life.

After a violent knife attack results in Vincent Taylor's death, his wife claims that she was the victim of an abusive relationship.

A mother's love is the most powerful in the world, for one Ohio woman, it will even overpower her fear of death; incapable of throwing out her dangerous son.

After a single mother fails to show up for work, police find her brutally stabbed and her daughter missing from their home in an affluent gated community.

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.

A crash on a North Dakota highway leaves one passenger dead, but the van's driver unscathed, and investigators see the passenger has deep stab wounds.

An elderly couple disappears one day and their bodies are found at the bottom of a well on their property, and the suspect is the couple's middle-aged son.

After a single mother fails to show up for work, police find her brutally stabbed and her daughter missing from their home in an affluent gated community.

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.

A crash on a North Dakota highway leaves one passenger dead, but the van's driver unscathed, and investigators see the passenger has deep stab wounds.

An elderly couple disappears one day and their bodies are found at the bottom of a well on their property, and the suspect is the couple's middle-aged son.

A mother's love is the most powerful in the world, for one Ohio woman, it will even overpower her fear of death; incapable of throwing out her dangerous son.

When single mother, 45-year-old Rainey Morin from Montana, begins a relationship with 46-year-old Robert Kowalski, she is unaware of his dark past.

Three men die over a span of a dozen years and no files are charged, but a new investigation begins, and all suspicion points toward just one person.