A reporter declined to reveal his source. Then police showed up at his front door with guns.

[Princess Turandot]

3. A commenter on the WaPo article described this situation...

...as "a slimeball vs goons".

This concerned the untimely death earlier this year of San Fran's 59 y.o. elected public defender, Jeff Adachi. (Its cause was reported preliminarily as a heart attack original.) Subsequently, a confidential police report, which included photos of the scene, made its way to this reporter/stringer, who then sold the info to media outlets:

On Feb. 24, ABC 7 published a story after it said it obtained a police report and photos about Adachi’s death, which included unflattering details about the public defender’s last hours. The story reported that he had been with a woman named Caterina — not his wife — and that he was found unresponsive in an apartment with “an unmade bed, empty bottles of alcohol, cannabis gummies, and two syringes that may have been left by paramedics.”

The publication of those details, which did little to illuminate the nature of Adachi’s death and more to call into question his character, prompted some to wonder if the police department was retaliating against Adachi, even after his death.

The criminal investigation referred to in the article is looking for the person who sent the confidential documents to this guy. The reporter has first amendment rights, of course; his use of them in this case perhaps helped sully a local hero's reputation. Since the SFPD as an organization is effectively being accused of being behind the leak, they're likely quite eager to figure out who actually did it.

The reporter also happens to be the registered owner of several guns, which may have contributed to the approach that the police took in executing the warrants.