Warning: The following article contains SPOILERS for Watchmen.
HBO's Watchmen's supplementary materials contain a tidbit that seems to disprove the fan theory that the late Judd Crawford (Don Johnson) was actually Dan Dreiberg AKA Nite Owl. Created by Damon Lindelof, Watchmen is a continuation of the classic graphic novel written by Alan Moore and illustrated by Dave Gibbons. The HBO series treats the text of the comics as canon and picks up the story over 30 years later. The setting has changed to Tulsa, Oklahoma, and Watchmen's world has been changed in the aftermath of the successful hoax Adrian Veidt perpetrated to save the world from nuclear war in 1985.
Watchmen's pilot episode, "It's Summer And We're Running Out Of Ice," introduced Judd Crawford, Chief of the Tulsa Police Department. Under Crawford's leadership, the Tulsa P.D. donned masks and took on secret identities as a response to the White Night, a 2016 attack on the police by the white supremacist terrorist group called the Seventh Kavalry, who model themselves on the late vigilante Rorschach. After three years of peace, the Seventh Kavalry declared war on the police and are on a mysterious mission; to retaliate, Judd and Detective Angela Abar (Regina King) AKA Sister Night led an offensive against 7K members hiding out in a cattle ranch. When members of the Kavalry tried to flee in an airplane, Judd shot them down by unveiling the Owlship, which was the futuristic signature vehicle of Nite Owl. The fact that Judd also kept a copy of Under The Hood, the autobiography of Hollis Mason, the original Nite Owl, naturally seemed like clues that Chief Crawford was Dan Dreiberg living a new life in Tulsa incognito.
Like the graphic novel, which concluded its first 11 chapters with supplementary materials about Watchmen's history, the HBO series has followed suit with the Peteypedia website, which is an evolving compilation of files by Agent Dale Petey of the FBI's Anti-Vigilante Task Force. In a detailed memo Agent Petey wrote to his colleagues titled "Rorschach's Journal" and dated September 1, 2019, there is a tidbit of vital information about the current whereabouts of Nite Owl: "Dreiberg, now in federal custody, has steadfastly refused to speak to the Bureau about “Rorschach’s Journal,” or anything, for that matter." This effectively shoots down the theory that Judd Crawford is really Dan Dreiberg since, according to Petey's memo, Nite Owl has been held in custody since he and Laurie Blake (formerly known by the superhero codenames Silk Spectre and The Comedienne) were arrested by the FBI in 1995 for violating the Keene Act by continuing their careers as costumed crime-fighters.
It isn't surprising that fans immediately assumed that Judd Crawford was really Dan Dreiberg: the unexplained fact that somehow Judd had possession of the Owlship pointed to Dreiberg living under another assumed identity as Crawford. (At the end of the graphic novel, Dan and Laurie took on the identities of 'Sam and Sandra Hollis'.) Judd was also clearly a fan of Nite Owl and was familiar with the careers of both men who took on that superhero mantle. Further, when the Tulsa police were attacked, Chief Crawford spearheaded their new mission to bring law and order while wearing masks to keep their identities safe - just like Nite Owl would have.
While other major Watchmen characters like Ozymandias (Jeremy Irons) and Laurie Blake (Jean Smart) appear in the HBO series - even Doctor Manhattan was shown on Mars in the pilot episode - the absence of Nite Owl naturally made fans suspect that the gadget-inventing superhero was already right there hiding in plain sight. And, because Judd is mysteriously killed - seemingly by Will Reeves (Louis Gossett, Jr.) - and found hanging from a tree by Angela, the fact that a major character is murdered in the first chapter of Watchmen echoes how the graphic novel began with the murder of Edward Blake AKA The Comedian, so it would have been symmetry if Judd/Dreiberg was the victim kicking off the events of HBO's series.
However, the Watchmen graphic novel's supplemental materials were canon so it's reasonable to believe that HBO's Peteypedia is also canon for the TV series. This means that, unless Petey is lying or misinformed and Dreiberg is not in federal custody (which seems unlikely), the late Judd Crawford can't be Dan Dreiberg and Nite Owl still lives in Watchmen's universe. Until it's confirmed in the series itself, however, it's understandable if fans have their doubts.
Watchmen airs Sundays @ 9pm on HBO.