For now though, I'll probably have to keep my civil engineering job...

The police will probably say it is a civil issue.....next

There are plenty of people who swear by not investing in condos but it just seems like they're just more risky with HOA fee hikes, potential litigations, etc.

They know they are taking a risk by exposing more than one property to litigation, but they reluctantly decide it’s worth it to avoid the headaches of having numerous LLCs.I recently bought several rental properties from an investor.

You can probably get out of this if that's what you want or at least the threat of litigation against the seller should get them to do the right thing if you still want the property.

My background is in commercial litigation.  

This is not a case that remotely justifies litigation or a lawyer.

If I lock them out, will.the police make me let them back in or can they legally break in or is their only recourse civil court? 

Using leverage makes you less of a target for litigation because there isn't a lot of equity in the property. 

Tax returns are also rarely relevant to a case and thus exchanged in litigation (check with your state's rules).