This property appears to be in Englewood, which has become notorious of late, as the most dangerous (deadly) part of greater Chicagoland.

However now that you "know" they have a violent past, in my not-a-lawyer opinion, you have a problem in that if anything happens with the other tenants you could be held liable for knowingly allowing a danger to persist in your building.So at this point unfortunately, you have to act.

Some end up here in the tech sector, and they put the bravest face on it they can, but the ones that are here often want out and are looking for every opportunity to get out.My brother came here in the late 90s to attend CMU and he passed on the same hopeful stories back then - Pittsburgh is changing, Pittsburgh is reinventing itself, Pittsburgh is become new and fresh and different, Pittsburgh will become a tech hub...I've heard over twenty years of broken promises like that, and so I'm not putting any money on the explosive potential of the tech industry to change everything in the region overnight.

This is a rescue loan, @Mary Ann Casey,  and a spectacularly dangerous deal for you to invest in.

Witness accounts mention explosions from the back porch.

Some of these areas are truly dangerous for your bank account.

From what I've read, it's not dangerous until it's disturbed and the dust is released into the air.

Using credit cards to rehab property is dangerous especially if you buy over priced items at the big box stores. 

No danger of the receipt being lost by either party.  

Banking on future appreciation is a dangerous tactic.