To save repetition, let's just stipulate that "shocking" describes every true-crime movie on this list.

Lots of excellent documentaries examine crimes — "The Times of Harvey Milk" climaxes with a murder and little-girl-becomes-art-superstar charmer "My Kid Could Paint That" may involve fraud — but, in my mind, a true-crime doc only pops if the crime itself is front and center. The Holocaust was criminal, for instance, but the many fine nonfiction films about it belong to a different category.

As shown in HBO's current true-crime series, "I'll Be Gone in the Dark," these are the kinds of stories that lead to obsessively tweeting about "Tiger King" (I have not seen it but, in any case, I'm only including feature films) or, in pre-social media days, jamming message boards with theories about the unbelievably twisty murder investigation of "The Staircase" (whose director made a previous, even better, movie you'll find on the list below).

Given our fascination with crime, there's no surprise it features in so many nonfiction films, but it is surprising it took Hollywood so long to take notice. Academy Awards have been handed out for documentary features since 1942 but no true-crime doc won until six decades later ("Murder on a Sunday Morning"). Trophies almost always went to World War II-themed documentaries before Oscar shifted its attention to nature films and then biographies, including 1957 winner "Albert Schweitzer," by St. Paul native Jerome Hill.

In keeping with an organization that has usually favored safety over risk, Oscar docs avoided controversy until the anti-Vietnam film "Hearts and Minds" won in 1974. An inspiring portrait continues to be the clearest path to awards — think of Muhammad Ali in "When We Were Kings" or last year's daredevil mountain climbers in "Free Solo" — but Oscar has begun to reward compelling filmmaking, not just compelling topics.

After years of pushback because of his use of dramatizations, Errol Morris finally won in 2003 for "The Fog of War." In the aftermath, documentaries have become even more open to experiments that get at deeper truths. It's exhilarating to see documentarians explore the possibilities of animation ("Waltz With Bashir"), re-enactments of events that weren't captured on film ("Man on Wire"), surreal storytelling ("The Act of Killing"), autobiography ("Faces Places") and personal essay ("Minding the Gap").

Those experiments demonstrate that there's no limit to what a documentary can do. These true-crime titles demonstrate there's also no limit to the peculiarity of the human experience.

Dear Zachary (2008)

Warning: It's a gut punch. Director Kurt Kuenne originally intended the film, which can be seen in its entirety on YouTube, for an audience of one: a baby named Zachary who never knew his dad, Andrew. He was murdered by Zachary's mother, who fled to Canada, launching a jaw-dropping sequence of events that ended in unimaginable tragedy and, ultimately, new Canadian laws.

Paradise Lost trilogy (1996-2011)

The story of the West Memphis Three has been told in numerous films and books but these movies, which follow the arrest of three Goth teenagers for supposedly satanic murders in Arkansas, were there from the beginning. Joe Berlinger and Bruce Sinofsky, who also made the heartbreaking "Brother's Keeper," about an elderly man on trial for the murder of his sibling, went deep, following multiple bad leads and false witnesses until the trail led to the truth.

Murder on a Sunday Morning (2001)

The only true-crime documentary Oscar winner is surprisingly obscure, given the phenomenon that was director Jean-Xavier Lestrade's next project, "The Staircase," the twisty true-crime series that kept adding new chapters as new developments surfaced over a 14-year period. Equally gripping, "Sunday Morning" is tidier — when it's over, you know what happened when a Jacksonville, Fla., tourist was murdered — but also turns on issues of truth and subjectivity.

Twist of Faith (2004)

Its startling intimacy comes from the fact that much of the footage was shot by the participants, who were hesitant to share their story. Ultimately, all is revealed in a conflict that comes to a head when a man, abused by a Roman Catholic priest when he was a teenager, realizes that not only has the priest escaped justice but he's his neighbor.

13th (2016)

Ava DuVernay's best film, currently free on YouTube, is this disturbing look at the legacy of the U.S. Constitution's 13th Amendment. Unlike others on this list, it doesn't concern one specific crime, but "13th" convincingly argues that, in a way, slavery never ended, continuing to the present with mass incarceration and an unfair justice system. Historian Kevin Gannon is one of many who argue that racism in America is a crime: "If we are Black, we are the products of history that our ancestors did not choose." The subjects include the Central Park Five, later the protagonists of DuVernay's "When They See Us."

The Thin Blue Line (1988)

Often pointed to as an example of the power of movies, Errol Morris' classic led to the release of Randall Adams, who had been wrongly convicted of the murder of a police officer. Weaving interviews and re-enactments while accelerating the pace of the story, Morris' film is a tense, provocative thriller — and it wasn't even the movie he planned to make. Morris stumbled on the case while researching what would eventually become his "Dr. Death."

Tower (2016)

My favorite of a very narrow subgenre of nonfiction films, animated documentaries, is this hypnotic one about shootings at the University of Texas in 1966. A gunman positioned himself in an observation deck and took aim at students and faculty, which this poetic film captures, with a special emphasis on the heroes who helped some people survive and others avoid danger. The animation is simple, beautiful and a unique solution for depicting events that left little video evidence.

Correction: Previous versions of this article misstated the title of a 2004 documentary. It is "Twist of Faith."