When I first started doing lending in Detroit.. this was an issue ... my client a big time flipper rehabber always had retired cops there with a clip board to check in the workers.. it was determined early on that much of the theft came from the exact guys that put the stuff in during the day.. they had the codes they knew what was there they would come in at night and steal it .the day cop and clip board put that to bed.So I agree with @Bryan Bannach  hire a retired policemen have him there during construction hours its the cost of owing property in the hood.. nothing unique about this.or just sell the property and buy something else.. but I think your looking to assemble so I know you probably don't want to sell.so just as stated hire security and I really like the idea of the @Patrick Liska  Cinder block fence I would for sure do that.. then put broken bottles in the concrete on top..

They are semi retired but probably have about 5-10 years of income left.

I also have roughly $30k in savings that I could use for my down payment with another $10k in reserves that I'm not willing to deplete.

If you're going through a realtor to purchase it that realtor should be giving you a discounted listing on the resale so that should save you a % or so.If you want to PM me I can comp it for you if you want another set of eyes on it

My primary objective is acquiring decent cash flow and the savings that I have aren’t tied to any kind of debt.

Mine did, and saved me (easily) the cost of tax prep; and I'd been self-preparing for over 30 years - - - during which time I now realize I paid some "stupid tax".Best to you - whatever you decide. 

I know with this being your first rental, the idea of vacancy is scary, but please trust me; a month of vacancy while you wait for a great tenant is going to save you thousands of dollars, hundreds of hours and immeasurable amounts of stress compared to what will happen if you pull the trigger on a questionable tenant because you are eager.

You could do it yourself if you're trying to save money although I would recommend you hire an attorney.

Save 10k , buy a 90k duplex :DI think if you start buying lotto tickets sometime next week, you should be able to raise 10k within a few months or so

I decided instead to save the $ and create organized systems that help alleviate some of the more tedious work that comes along with managing the properties myself.