https://www.mcsweeneys.net/articles/an-interactive-guide-to-...
Stick around for the (genuine) statement from a police department at the end, and its translation.
Calling it an "officer-involved shooting" (should have a hyphen!) in an initial report restricts the scope to a just-the-facts-as-we-know-them-m'am style. Even from the headline I know: 1> where (Fremont), 2> Fatality, 3> cop was there. Hopefully the first paragraph tells me who shot whom and some macro facts.
But in an early article or "hot take" it's rarely clear if, for example, a cop used excessive force, or poorly pressured someone under stress so they took their own life; if there was legitimate responsibility etc. The passive voice here preserves the "innocent until proven guilty" position.
If the cop is later convicted of murder I would hope that a subsequent news article would be more definite ("officer XXX convicted of murder") or alternatively "Letter: distraught father wanted suicide to be a spectacle"
In fact this is why I am generally uninterested in "news" -- the amount of actual data in these early articles is usually quite small. If people are still talking about it a week later, perhaps it's worth learning about.
Nevertheless, "officer shoots X" is at least as factual and without spin (unless X is "victim" or some kind of loaded word).
OP wasn't about news articles, anyway. In this context, the use of OIS from a precinct press release (i.e., a document not from a neutral observer, but from a representative of one of the involved parties) looks like an attempt to pre-emptively disclaim even the possibility of responsibility, which may or may not exist in any particular case.
“One Dead in Fremont Officer Involved Shooting”
Officer involved? The wording pretends that the police officer was a prop on the scene or some uninvolved bystander, rather than a real person who did a real thing. Re-write it as, "Police officer shoots and kills someone in Fremont". Much more accurate, but you'd never see a press release like this because it correctly describes the police officer as the starring role rather than as a prop in a situation that just spontaneously happened around him.
Think about this style the next time you read some press release where a company is responding to being accused of bad behavior, you'll see it everywhere: Anything about the company's actions will passive and it will be hard to figure out whether anyone in the company actually did anything: "A situation occurred. Procedures were followed." Conversely, anything about the accuser will be active and impart agency: "She became uncooperative. He yelled and acted threatening." It's a deliberate rhetorical tool, and I'm grateful this article gave it a name and described it so clearly.