It’s almost certain there’s no criminal case related to the death of the co-owner, even if the warrant should not have been issued. The fact is it was issued by a judge, and it doesn’t sound like the police did anything specifically outside the scope of the warrant.
If the warrant was issued illegally and there was some provable animus on behalf of the police, and/or it was done as clear harassment, a civil case is the most likely to succeed. By establishing certain facts such as these and proving the degree of distress caused, they can likely bring about a significant judgement against the city and possibly go as far as a sanction on the judge depending on how she was involved.
If it turns out it was a conspiracy between the restaurant owner and the police where they conspired to manipulate the judge into issuing an illegal warrant, the restaurant owner is the most likely to face a criminal charge.
I suspect they will also pursue a criminal or civil case on the basis of harassment of journalists doing protected work based on a false identity theft assertion to justify avoiding the legal requirement to issue a subpoena rather than a warrant. The co-owners death won’t be a material fact in that sort of case but I’m sure would be mentioned to sharpen the case.
Regardless I expect popcorn is warming all over the country among folks with an interest in law.
The death would absolutely be relevant in a criminal case (e.g., under the applicable federal statute matching the described conspiracy against protected conduct, it changes the maximum penalty from ten years to death or life in prison), in a civil case, it may also be relevant, as it would likely be among the harms forming the basis for damages. (It may even be the basis of the tort, e.g., if pursued as wrongful death, where the part you describe is the “wrongful” part.)