The show ran to 82 episodes and for the life of me I don't recall ever seeing one of them. I went digging around YouTube and found these opening credits, but it's not ringing any bells.
Robert Blake had an interesting career, capped by a trial in 2002 for the murder of his wife, of which he was acquitted, although he was later found to be liable for her wrongful death at a civil court case in 2005. Wikipedia has more details.
The Baretta Annual from Brown Watson was the usual mix of stories, strips and features. This is one I had down as being by Steve Moore, although he later said that he couldn't remember what his contributions were. Like me and the programme, nothing rang any bells.
The artwork is by Ron Tiner (strips), John Bolton and, possibly, John Peter Britton. I'll post examples from all three over the next few days and maybe we can get some confirmation of the latter's contributions (if any). First up, the strip that opened the book, drawn by Ron Tiner...