I dont think anyone, including physicians could point their finger to 1 drug or substance and say "AH HA its because of that!" But certainly diuretics, high protein diet, AAS, script pain killers (although morphine, nubain etc aren't typically nephrotoxic), advil etc can all add to his kidney problems.
Chick is right that AAS alone aren't typically the culprit of kidney failure. you worry more about liver issues, transaminitis, there is even some literature that suggests that AAS can cause benign cystic liver lesions which although benign, can rupture and cause issues.
but certainly HTN and DM can damage the kidneys... with AAS, insulin, GH potentially causing HTN and DM.
This is sad news for Luke, he seems like a good person and I wish him well. At the same time, I am sure he knows that he is the cause of his condition and will have to man up and deal with the cards that are dealt.
-A Dub