According to newly filed court documents, television network Al-Jazeera relied on a “highly reputable law firm in Washington” to buttress claims about athletes’ use of performance enhancing drugs that are now at the center of a contentious defamation lawsuit.

The source of those claims—aired in a 2015 documentary by now-defunct Al-Jazeera America—was Charlie Sly, a 31-year-old who was presented as a pharmacist and said he supplied performance-enhancing drugs to high-profile athletes.