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..

You could request you contractor put together a materials list and you pay for it, have your contractor go get the supplies for the week that they need and pay for it over the phone when they are at the checkout stand are some options.In order to check they are competent, you can do this one of three ways or all three ways.

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.

There are probably some great deals in far western MA, but if you don't want to be a 3.5 hour drive away from your investments, it's not going to work.  

I heard on a BP podcast today, "Calculate three Buy & Hold deals every morning." 

Within a few minutes to a few hours, the funds from C's bank are used to pay you and you sell the property to your buyer C.

I tell people I do not have time as I am spending it on clients who have made a commitment to me for my time and services.If I make thousands per hour for my time then someone asking me for free crap is not only not bringing me money in it is taking money  out of my pocket because I can use that time for clients.What might be better is paying for ongoing consulting services.

In the purchase contract, it stated that i was supposed to receive a copy of the keys to the property at close of escrow...All seemed well and i felt like i covered my basis.. this is where it goes haywire:15 days after close of escrow I still have not received the Keys; i've noticed them multiple times that i want to enter the property (24 hour notice) and they do not respond.

This particular outfit was one of three locations owned by same operator.

I am in the Westchester,NY area about an hour north of NYC if that helps.Thank youJimmy