syringes found in a backyard behind an A/C unit

See this message from a neighbor whose rear faces Crispus Attucks Park:

Sent: Saturday, December 12, 2015 7:45 PM
To: 'Scott Roberts'; 'Austin Pearl' <5E08@anc.dc.gov>
Subject: neighborhood activity

  

What I am about to mention is not going to be surprising, just thought I’d keep the neighborhood apprised.

   

This weekend I swept  up the leaves in the area going down to my basement.  Behind the AC unit there were 4 syringes, 3 looked unused.  I threw them in the trash.

    

I know that there has been people, or a person, down in that area before.  This is just to document activity. 

generic image of a syringe