Investigators search for a New Mexico mechanic who has been missing for eight years.

When a woman disappears after an encounter on a train, her family hires detectives to investigate.

A troubled marriage, then suddenly a man disappears, leaving behind a daughter and step-son. The truth from a secret kept for over eight years. Andrea Canning reports.

In Someone Was Watching, Cristi Hall, who appeared to have a perfect thirty-year marriage to Chris, but was found dead in the backyard spa. In The Ballad of Mike & Dalia, a story-book marriage, lust, greed and deceit led to an elaborate murder plot that makes reality TV look like a fairytale.

In October 2009, James Arthur Ray, a renowned self-help author and speaker, held a "Spiritual Warrior" retreat in Sedona, AZ. Three people died during the retreat, and Ray was charged with manslaughter but convicted of a lesser charge.

A couple meets at the craps table in Las Vegas. She was a beautiful trapeze artist and he was a professional poker player -- with a secret. Did he take a gamble that led to murder?

The case against Michael Jackson’s doctor, Conrad Murray, is in the hands of the jury, who will decide whether he played a role in the death of the pop star.

A fatal car crash in Montana may not have been an accident after investigators find a revealing set of text messages.

Tom Foley is shocked to find himself the lead suspect in the case of his wife Darlene's murder. Thinking the case was over, the defense team is soon approached by a stranger with new evidence that would turn everything upside down.

A vacation in Aruba that morphed into a mystery, Robyn Gardner went missing and many presume she's dead.

Susan Cox Powell is a young mother from Utah who suddenly disappears on a winter night in 2009. Dateline NBC's Keith Morrison reports.

10 Years ago, the accusation that Penn State Coach Jerry Sandusky sexually abused a child, came to the attention of Ray Gricar, the local district attorney. 3 years later Gricar went missing. His laptop was found but the hard drive was unreadable. Could Gricar’s disappearance be linked to the Sandusky scandal? Lester Holt reports.

Millen, Georgia, a small industrial town so devastated by the Great Recession, its unemployment numbers peaked at 21% - more than twice the national average.

The story of an unsolved case involving a woman's love triangle that ended in her husband's fatal stabbing in front of their home, but more than two decades later, detectives have re-opened the case and need her help.

Couple on a honeymoon cruise when George went overboard. An active, ongoing investigation. Royal Caribbean has conducted an investigation about what happened aboard the ship.

Jennifer Hudson talks about her weight loss, healthy living tips, details of her upcoming nuptials, and more. Also the story of a mother who was found dead in her car off a lonely dirt road. With no arrest in the case, strange sequence of events led investigators to an unlikely suspect.

Investigators find an unlikely suspect in a woman's death.

A woman seeks justice for her 18-year-old daughter, who was raped and murdered in an Anchorage state park in 1994.

Police suspect a woman's estranged husband in her stabbing death, but surveillance video shows he was not at the scene.

In the lead up to a murder trial, it begins to look like police arrested the wrong man.

Two years after the disappearance of his wife, Josh Powell kills his two sons and himself.

TV producer Bruce Beresford-Redman and his wife Monica who were vacationing with their family at a luxury resort in Cancun Mexico in April 2010. But when Monica was later found dead on the hotel property, Mexican investigators now had a murder mystery on their hands...and a primary suspect, her husband.

Millionaire developer Bob Ward dancing in his cell just days after his wife, Diane, was shot to death in their Florida mansion. Did the husband pull the trigger? The police think so. His daughters disagree. What will a jury decide?

Inner-workings of Reliable Day Care, a modern day "social norm" of American child rearing. Not all Day Care operators are who they seem to be and may actually be dangerous.

The process pharmaceutical companies go through to get a new drug tested, approved, and available to consumers. It may not be as careful as people are led to believe.

In 2009 a Los Angeles police detective examines the cold case file on an attractive nurse, Sherri Rasmussen, who was murdered in her own home in 1986. At the time it looked like a botched burglary, involving two men but a bite mark containing saliva is found on Sherri's arm and reignites the investigation.

A group of undercover investigators try to uncover the reason that some lottery retailers actually end up with winning tickets, while the customers who bought the tickets walk away with nothing.

A father is murdered in broad daylight after he dropped his son off at a daycare and the culprit is as surprising as the reason that the father was targeted for murder.

A man with a surprising motive shoots a father in broad daylight.

A young man with a new love goes missing, and family members and detectives crack the case by connecting a series of seemingly random crimes.

Lester Holt travels to Florida to report the latest information on the story of Trayvon Martin, an unarmed teenager who was killed by a neighborhood watch member; Chris Hansen confronts companies making false promises about their insurance coverage.

Michelle Young, a 29 year-old woman from Raleigh, N.C., who was found murdered in her home while her husband was away on a business trip and why it took five years to convict the woman's killer. Keith Morrison reports.

Michelle Young was pregnant when she was brutally murdered while her husband was away.

A woman accuses her boyfriend of rape and finds herself on the wrong side of the law. A he said, she said case turns into a quest for revenge.

A divorced mother of four children, who was accused of a heinous crime and then served 15 years in prison for the same wrongdoing even though there are many that claim the horrible crime never actually happened.

A look into how much parents and children really know about the danger of abduction; as a test, elementary school children are offered a tour of an ice cream truck and a stranger asks young teens for their names and personal addresses.

A millionaire from Newport Beach who was murdered in 1994, the investigation went cold, but 15 years later his widow and an ex-football player were arrested for the crime.

A man accused of murdering a prostitute in 2003. His wifevrecently testified against her husband and revealed that he confessed the murder to her before threatening her into silence.

A Penn State professor and consultant to MADD, investigate what really happens when teenagers start driving; teenagers are tested in three different and potentially dangerous driving situations.

Meredith Vieira interviews 11 year-old Sean Goldman, the boy who was kidnapped by his mother when he was four and taken to Brazil, about the entire ordeal, the repercussions in his life now, and what it's like to live with his biological father.

Natalie Morales and Rosalind Wiseman, an expert on teen ethics and behavior, investigate what happens when teens are confronted with the temptation to cheat: tests include using cell phones during tests and changing scores in athletic drills.

The story of Ben Oxley, a 36 year-old who was murdered while he was asleep next to his wife, and new reports about how the accused murderer was able to break in to the house, and leave without leaving any trace of forensic evidence behind him.

Despite the fact that the current generation of American children is the most diverse in history, some teens may not know what to do when confronted with racial and ethic discrimination and how damaging such occurrences of discrimination can be.

Jane Bashara, wife and mother of two from upscale Grosse Pointe Park, Michigan, is found murdered in her Mercedes SUV that’s been left in a seedy Detroit alley. Her husband's secret life makes the police suspect that he may have been involved in the murder.

A boy who claims that he is victim of bullying is charged with manslaughter; Colonel Greg Gadson shares his inspirational story; Chris Hansen investigates Tronix Country's business deals; an update from a small town affected by the Great Recession.

Keith Morrison reports the story of Steven B., a radio DJ who was found dead in the waters off of Catalina Island, and why solving his murder took five years.

After a prominent attorney from Nevada is found murdered, the investigators were led to two suspects, but could not determine the nature of their relationship.

A former radio DJ and multi-millionaire disappears from his yacht in the Pacific Ocean, but investigators discover he didn't drown.

An Iowa mother, home alone with her three kids, is attacked and the confrontation turns fatal. But is the truth more twisted than anyone could imagine?

A college student is murdered in her Dallas condo. Although there are a few possible suspects, the case eventually goes cold. Years later, her friend’s calls to the police lead to the case being reopened, and eventually solved.

Keith Morrison reports the story of a young woman who died after having a spray tan.

A look is taken at the story of a high school valedictorian who was murdered in Montana and the new witnesses who could change the 30 year-old story.

A look is taken at the story of Esther Pilgrim, the woman who was conned by former rap star Tim Dog in an online dating scam, and how she plans to get revenge.

Officials identify a man's remains more than 20 years after his mysterious disappearance.

Dateline cameras roll as three formerly middle-class families confront poverty for the first time.

"The Last Dive" examines the case of Shelley Tyre who drowned mysteriously while scuba diving with a companion in the British Virgin Islands. "Buried Secrets" examines the disappearance of David Jackson. After his body is discovered twenty years later, a rookie detective helps find the murderer.

Investigating the mysterious murder of a family patriarch.

The killing of 12 people in Aurora, Colorado during a screening of the new Batman movie. Also, A young college student vanishes late one night; ten years later, her mother's persistence and a new investigator help reveal the shocking truth about her sudden disappearance. Josh Mankiewicz reports.

The story of two strangers who were brought together by a unique bond that goes back to the Civil Rights movement; an investigation of the murder of a family patriarch and the detective who finally trapped the true killers.

Tim Permenter calls 911 to report a horrible discovery; his girlfriend Karen Pannell, a one-time model and flight attendant, has been murdered in her kitchen. On the wall next to her body is a message written in her own blood: the letters R O C. What does it mean? Dennis Murphy Reports.

A young woman from Southern California goes missing. Did she run away? Was she kidnapped? The police have suspects but no real evidence. It would take over nine years and the expertise of a cold case investigator, The Evidence Whisperer, to figure out what happened to Lynsie Ekelund. Josh Mankiewicz reports.

The heartbreaking case of Angie Dodge, an 18-year-old woman murdered in her home in Idaho Falls, Ind. Her mother fights to free the man (Chris Tapp) convicted of murdering her daughter. Keith Morrison reports.

The disappearance of a young woman from Denver and the near fatal attack of another young woman in a neighboring town. Keith Morrison reports.

A fast-talking hood risks his life by going undercover in one of the country's roughest prisons to expose a suspected serial killer’s secrets.

A look is taken at a the story of an escaped convict and a deputy warden's wife who were found after a decade on the run and if she a hostage or accomplice.

A mother of three who was killed on a lonely dirt road just a mile from her home.

The latest in the story of Drew Peterson, who has been found guilty of murdering his ex-wife.

Lester Holt talks to Gabby Douglas during her first week after the London Games about her plans for the future; an undercover investigation of air conditioner repair companies; a look at how carnival games work; Hoda Kotb interviews Steve Harvey.

Some of the most amazing moments of athletic adventure ever caught on tape. More than extreme, these are life and death situations, and sometimes it is the spectators who are in peril. From mountaintops to ocean depths, you won't believe these people are alive. Also, Kate Snow reports live from the scene of the tragedy in Aurora, Colorado with the latest news. Survivors who were inside the movie theater speak out.