A mortgage is a lien collateralized by real estate, not a person.The taxing authorities will obtain ownership information through the county recorders office.  

I installed NoiseAware in the common hallway, but convinced that it does not accurately record the volume.

Especially anywhere in California, and particularly Los Angeles county.Talk to longtime neighbors who might know story and whereabouts of owner, but don’t accept as fact.I’d start with researching who the record owner is.

Ensure you have reserves for vacancies or repairs, properly screen tenants, switch to landlord insurance, and keep detailed records for tax time.

You’ll need to handle inspections, work with housing authorities, and make sure your tenant screening process is solid.

I'd be surprised that you couldn't find several HML with that record, assuming you haven't defaulted.

I’ll also call code enforcement and check the county records just to see when things like roof/hvac have been done/permitted. 

More bonus points if it could look back at the borrower's track record and predict how they will do on a particular type of rehab?

Lemos: Quote from @Jay Hinrichs: well there is a few ways you can do that.. and Assignment gives the world notice that you own your % as its recorded at the county recorder. 

We’re at or near record low foreclosures, you’re farming a hard row.