In an unpublished decision, the Fourth Circuit determined that Washington DC's drug statutes are divisible. In so doing, the Court permitted reference to a statute (outside of the statute of conviction) that contained a list of criminalized substances as part of a modified categorical approach.
The full text of Carcamo v. Lynch can be found here: http://www.ca4.uscourts.gov/Opinions/Unpublished/151005.U.pdf