You'd be surprised what information is released to the public. I'd be willing to bet that the reporter has access to dispatch logs from over-the-air radio [1] and cross-references that with incident reports at [2] and then does a lookup on [3]. Entirely speculation, but it's not implausible.
Absolutely, there are many data sources available so piece some of this together.
What I find interesting is indicating a LinkedIn profile, unless of course this reporter has access to investigation documents that also identify the LinkedIn profile.
It could very well be a different person with the same name in the same town. Why take the risk? Just so you can have the juicy headline "alleged killer also worked in tech."
[1] https://somafm.com/scanner/ [2] https://data.sfgov.org/Public-Safety/Police-Department-Incid... [3] https://www.sfsheriff.com/find-person-jail