I found this nicely written article on nytimes.com. If you were this guy would you have done the same thing?

ONE hot night last summer, just past midnight, I discovered that in the apartment building across the street from my duplex in Fort Greene there was a little crack house.

I was parking my car after a late movie, the windows down because my air-conditioning was broken, when I heard a man and a woman arguing on the sidewalk. I didn’t know them, but they weren’t new faces to me. In the four years I’d lived in the apartment on South Oxford Street, I’d walked past them many times. They were constantly moping around the block with glassy eyes, scratching themselves, and muttering. Any New Yorker could tell they were crackheads.

I never gave much thought as to why these two crackheads were on my block so often. Some days in Fort Greene you walk past celebrities like Adrian Grenier or Colson Whitehead or Mos Def. Some days you walk past a crackhead.