Dateline NBC

The suspicious death of Sarah Hartsfield's fifth husband leads investigators to a past filled with failed romances and wild allegations.

A house fire in South Texas kills Patricia Leigh Mills while her young son miraculously escapes. When Patricia Leigh's widower, Delbert, marries a woman named Allison less than 3 months later, her family becomes convinced he was involved. After Allison is arrested in a murder for hire plot, the question remains: did Delbert have help?

INTERVIEWS WITH: Delbert Mills, Patrick and Allison Salinas. 

Jimmie "Jay" Lee, a popular and beloved student at the University of Mississippi, vanishes from his apartment early one July morning and is never seen again.

Officials quickly rule a Georgia man's death a suicide after his wife tells authorities that he shot himself; believing there is more to the story, his family hires a private investigator, who uncovers troubling details.

When American University professor Sue Marcum is found murdered in her Maryland home, it appears to be a burglary gone wrong. But DNA from the scene tells a different story, pointing detectives toward someone she trusted. A years-long international hunt leads to a dramatic arrest and long-awaited justice. 

INTERVIEWS WITH: Sue's brother and his wife Alan and Barbara Marcum, FBI agents in Baltimore and Guadalajara, Prosecutors Debbie Feinstein and Ryan Wechsler, Defense Attorneys Meghan Brennan and Tatiana David, and others.

A wealthy podiatrist and his girlfriend plot to hire a hit man to kill his wife, but the would-be assassin alerts police; years later, a shocking new chapter after their release, as one of them allegedly attempts to revive the murder plot.

In her first interview since her mother's disappearance, "Today" co-anchor Savannah Guthrie recounts her family's fears and anguish, as well as their hope for answers.

Dateline examine the case of Brendan Banfield, the Virginia father found guilty earlier this year of murdering his wife and a second victim in a case that captured global attention.

The broadcast features never-before-seen footage of the family's au pair, Juliana Peres Magalhaes, speaking with police following the killings, prior to pleading guilty to charges related to the case. Authorities later revealed she had been involved in a relationship with Banfield and colluded with him in the murders.

Alice Ku, a California tutor, vanishes during a trip to Taiwan. Her family embarks on a desperate search spanning two continents but as investigators dig deeper, secrets emerge and a trail of digital evidence contradicts everything they thought they knew.

INTERVIEWS WITH: Alice's sisters Josephine and Grace Ku, civil attorneys Andrew Watters and Todd Davis, defense attorney Chuck Smith and more.

Found Guilty of Shooting His In-Laws, Serafini Maintains His Innocence & Says He Was ‘Crucified' By Jury: ‘The Justice System Failed'.

In his first-ever interview, former MLB pitcher Dan Serafini speaks with Dateline correspondent Keith Morrison. In the exclusive sit-down, Serafini maintains his innocence following his conviction earlier this year for shooting his in-laws at their home in Lake Tahoe. 

The broadcast also features interviews with key figures in the investigation, including Detective Daniel Meier, Placer County District Attorney Morgan Gire and more.

The latest developments in the case of mother-of-three Kouri Richins, who wrote a children's book about grief and was recently found guilty of murdering her husband, Eric.

Broadcast will include new interviews with key figures connected to the investigation including Richins' brother DJ, who is speaking publicly for the first time since the verdict.

When a law student is found murdered in her home, suspicion falls on someone close to her; for years, her family searches for answers as the case goes cold; decades later, renewed attention leads to an arrest and a dramatic courtroom twist.