The BC case is definitely one of the more infamous unsolved crimes out there.
I have seen the well-done movie Auto-Focus (2002) several times over the years - this starred Greg Kinnear as Crane & Willem Dafoe as John Carpenter. This focused on BC's "double-life", and ended with his gruesome fate. Solid film, but definitely not for the squeamish. One of the many elements of AF that was especially impressive was that the crime scene at the end of the film recreated the actual crime scene very closely.
I don't have a strong opinion on who killed Crane. Given that there wasn't any sign of forced entry, when I first started reading about the case it seemed like the perp. was someone he knew & possibly let in himself...and/or someone who had a key to his place. However, IMHO it's also possible someone could have picked the lock and/or gotten in another way - maybe.
If this crime had occurred today, I speculate that with the advances in DNA technology/forensics & the fact that security cameras are much more prevalent now - it would possibly have been solved.
To those who are interested in this case, there is a decent doc. out there called Murder in Scottsdale: The Death of Bob Crane (2003). It focuses on the crime & the investigation, and seems thorough. Though, I don't necessarily agree with all of the views here.