Behind the scenes, a small team of FBI agents spent years trying to solve a stubborn mystery — whether officials from Saudi Arabia, one of Washington’s closest allies, were involved in the worst terror attack in U.S. history. This is their story.

How the media and law enforcement fingered the wrong man for the 1996 Olympic Park bombing.

Whenever the black dress came out, Jessica Weisman’s mother knew she was “going after the Jewish people again.”

For years, the clients of a Colorado funeral home kept their loved ones’ cremated remains. Then the FBI called.

Inside a sleazy FBI sting involving diet clinics, fitness models, money laundering, and a supposed plot to hire a hitman.

Twelve years ago, a Saudi Arabian man, whom federal authorities had long suspected of having ties to terrorism, was sentenced to life in prison on multiple counts of unlawful sexual contact. To this day, al-Turki has maintained that he’s innocent and was instead the target of post-9/11 anti-Muslim sentiment.

Twenty-five years after 82 Branch Davidians and 4 federal officers were killed, the lead negotiator at the scene is still arguing about what happened.

How the ex-spy tried to warn the world about Trump’s ties to Russia.

To the KGB and back.

Deep Throat, unmasked.

The documentary filmmakers from Longbow Productions said they wanted to tell the story of the Bundy Family and their standoff with the government. Their cameras were real, but the people behind them were undercover FBI agents.

A report from inside the FBI.

The story of William Morgan: American, wanderer, Cuban revolutionary.

The search for the world’s most elusive skyjacker.

In 2001, Maksym Igor Popov defected to work as an informant in the U.S. But a decade later, he was back to scamming the FBI.

Their entire lives, Alex and Tim Foley thought their mom and dad were typical, boring American parents. Then the FBI showed up.

Bill Landreth was one of the whiz kids, poking around Pentagon servers with the friends he had never met. But one of them was an FBI informant.

For immigrants from Muslim-majority countries, applications for visas, asylum, green cards, and naturalization can take decades. Unless you’re willing to be an informant for the FBI.

First they found his server, then they found his name. But if they couldn’t catch him with his laptop open, the whole thing would fall apart.

The murder of a 34-year-old by a wig-wearing figure traces back to meth, an FBI sting and a former municipal judge who once sent a live copperhead snake to a foe through the U.S. mail.

The transcript of chats between Silk Road boss Ross Ulbricht and a man he believes to be a Hell’s Angel who agrees to supply “hitters” to carry out 5 assassinations.

In March 1971, John and Bonnie Raines broke into an FBI office, stealing documents that revealed that the government was spying on its own citizens. Today, they’re hailed as heroes. Is this what the future holds for Edward Snowden?

The saga of Naji Mansour.

A triple homicide, the alleged involvement of a Boston Marathon bombing suspect, and those caught up in the FBI’s ongoing investigation.

On then-agent, now-congressman Michael Grimm and what happens when an F.B.I. informant turns out to be a con man.