The original article "Imaginary Chechens Attack!", has been relocated to the Ghosts of Alexander blog.

Joshua Frost has also covered the topic at Registan.net:

Framing the Threat, 5/30/09
Army Major Disputes Story of Chechen Fighters in Afghanistan, 7/3/09 (see the comments as well)


From another thread:
Quote Originally Posted by Deus Ex View Post
I've know a captain (now major) who deployed with special forces to Afghanistan and personally killed Chechens.
If you read "House to House" about the Battle of Fallujah, Chechens were recorded as being there.
Just saying.
Everyone here knows someone who has personally killed “Chechens”. It is not a question of if they were fighting foreign fighters or not, but rather if they were fighting actual Chechens. Not Uzbek, Azeri, Turkish, Nogai, Ingush, etc; but Chechen.

How did he know he was Chechen?

It is not easy to prove, and the evidence for significant groups of Chechens in Afghanistan is minimal. I have also yet to read the name of a single Chechen fighter killed in Iraq or Afghanistan in a public source, and I literally have hundreds of articles on Chechnya and Chechens.