Unknown Serial Killers of America
Hayu/Oxygen anthology docuseries, 2025 — six forgotten American serial killer cases
Quick facts
What Is the Series About?
Unknown Serial Killers of America is an anthology documentary series that premiered on Oxygen in the United States on May 18, 2025, and became available to international viewers on Hayu beginning May 19, 2025. Each episode runs approximately 43 minutes and profiles a different real American serial killer — specifically offenders who, despite the scale of their crimes, have remained largely unknown to the general public. The first season comprises six episodes, airing weekly through late June 2025.
The series central premise is a deliberate pivot away from the household names of true-crime culture. Rather than revisiting Ted Bundy or John Wayne Gacy for the hundredth time, the production turns its lens on killers whose names rarely appear in popular documentaries, podcasts, or streaming catalogues — yet whose crimes were no less devastating to their victims and communities.
The Cases
Episode 1 — Carl Watts
The season opens with Carl Watts, who was active across Texas and Michigan during the 1970s and 1980s and who ultimately confessed to killing 12 people. Watts is regarded by some investigators as one of the most prolific serial killers in American history, yet his name has never achieved the cultural notoriety of his contemporaries. The Carl Watts episode examines his methods, the challenges investigators faced in linking him to multiple jurisdictions, and the circumstances that led to his eventual confession.
Episode 2 — William Suff
The second episode centers on William Suff, whose case involved the serial murder of sex workers. Suff's crimes and the investigation that eventually brought him to justice form the core of this installment.
Episode 3 — Daniel Conahan
Airing on June 1, 2025, the Daniel Conahan episode documents another case that flew largely under the national radar. The episode examines the investigative process that led authorities to Conahan and the evidence that ultimately built the case against him.
Episode 4 — Terry Rasmussen
Perhaps one of the most chilling cases in the season, the Terry Rasmussen episode aired June 8, 2025 and focuses on the discovery of multiple unidentified bodies found sealed inside barrels in a New Hampshire forest. Decades passed before investigators were able to link the remains to Rasmussen, a predator who systematically changed his identity after each killing, making cross-state connections nearly impossible for years. The Rasmussen episode holds a 6.4/10 rating on IMDb.
Episode 5 — Maury Travis
The Maury Travis episode aired June 15, 2025 and examines one of Missouri and Illinois's darkest chapters. Beginning in 2001, the bodies of 12 Black women began to surface across both states. The Travis episode also confronts the broader context in which these victims received far less media attention than victims in comparable cases involving different demographics.
Episode 6 — Herb Baumeister
The season finale, airing June 22, 2025, profiles Herb Baumeister, whose crimes targeted young gay men in Indiana during the 1990s. The episode gives notable attention to an amateur detective whose dogged pursuit of clues helped break a case that official investigators had struggled to crack. The Baumeister episode is the season's highest-rated installment on IMDb, earning a 7.2/10.
Production
The series is produced in an anthology format, with each self-contained episode functioning as a standalone documentary on its subject. Episodes clock in at approximately 43 minutes, a lean runtime that critics noted keeps the pacing brisk without sacrificing substance. The production follows a structure familiar to true-crime documentary viewers: archival materials, reconstructions, and testimony from investigators, journalists, and in some cases people connected to the victims or their families.
No single director has been publicly credited across available sources for the full season. The series is listed on IMDb under title ID tt36984001 and is classified as an ongoing series, suggesting additional seasons may be in development or production.
Reception
Critical response to Unknown Serial Killers of America has been measured but largely positive within the true-crime community. A review from Culture Mix described the series as a straightforward, no-frills, well-edited true-crime documentary and recommended it specifically to viewers with an appetite for lesser-known cases. The same review highlighted the series approach to its victims, noting that it values the victims and their loved ones rather than sensationalizing the perpetrators.
Audience ratings on IMDb reflect moderate but genuine engagement. The Herb Baumeister episode leads the season with a 7.2/10, while the Terry Rasmussen episode sits at 6.4/10. No major controversy has been identified in connection with the series, though the subject matter involving real victims, many of them from marginalized communities, inherently demands sensitivity in presentation.
The Cases Today
For several of the cases profiled, the legal proceedings concluded years or decades before the series aired. Carl Watts died in 2007, and his criminal history was largely settled before that point. Terry Rasmussen died in prison in 2010, but the identification of his barrel victims continued as an active forensic effort well into the 2010s and beyond, with DNA technology eventually helping to put names to the remains.
Herb Baumeister died by suicide in 1996 before he could be charged, meaning no criminal trial ever took place. For the victims families profiled across all six episodes, the series represents something the true-crime genre can at its best offer: public acknowledgment of lives that were taken and stories that were never told at scale.
Unknown Serial Killers of America is available to stream on Hayu internationally and aired on Oxygen in the United States beginning May 18, 2025.
