[hanamizu]

But how can a resident of the District legally acquire a handgun in D.C.? Are there any gun stores?

[TexasGurl24]

Yes. There are two:

https://www.dcsallc.com

https://www.ganddffl.com/

[Sgt_Schultze]

The story says he is a 42-year old Maryland resident.

Here's a link to a Kenneth Miles Davis, 42, from that area, with a previous firearm violation (you have to agree to the site terms, then re-paste the link to get in)

http://casesearch.courts.state.md.us/casesearch/inquiryDetail.jis?caseId=0P00103124&loc=17&detailLoc=ODYCRIM