Correct indeed, and this happened almost 7 years ago... I found the beetle inside my house (upstairs, in fact!) After the photo session I took it outside and freed it. I don't even live in that house anymore, though I'm still in LA County.

I've been going through my past photos and identifying them... It was a big surprise to find a probable non-native insect among them! It's exciting even now... it would've been absolutely thrilling if I'd known then. I'll definitely be more diligent about identifying insects now!

I'll do a little research, maybe this evening, and see what I think about the ID.

Of the spp. on the California checklist, the most likely candidate seems to be Nicrophorus nigrita (compare with N. humator). Adventive Silphids are always possible of course but, I'm skeptical.

Oooh, thanks Phillip. I probably ignored that possibility because there was only one image, and it didn't show the beetle's pointed abdomen (if I even came across it in my search — I don't remember for sure). (Not to mention that it's a dead specimin, which puts me off.)

The indented stripes on the elytra of Nicrophorus humator are more pronounced than those on Nicrophorus nigrita, whose scutellum is also larger. Both these things make the latter a closer match to my specimin, even if the locale is not considered.

I do see some differences in the pronotum (even accounting for lighting differences, I think) but that's just individual variation, right? Is there any reason not to treat it as a positive identification at this point?

unless someone has better idea, I'm comfortable this is it