I mean, it’s the county sheriff. Do you have a better source?

No, I haven't evaluated it beyond what I've said here.

But up thread you claim that the people detained and placed in unmarked vehicles are listed there. I was wondering how you had determined that, or if you were assuming it to be true, or what.

Do a search for “releases in last 7 days”, look through the names and you’ll see that the arresting agency was “DHS” or “US Marshalls” and it will see say “no charges filed, release on X/X/X”.

Which does not address the question of whether all the people detained and put in unmarked vehicles are listed there.

It just demonstrates that some people detained in Portland have been detained by officers working under those entities.