From Dexter Filkins, The New York Times:
Even in a country beset by murder and death, the 16th Brigade represented a new frontier.
The brigade, a 1,000-man force set up by Iraq’s Ministry of Defense in early 2005, was charged with guarding a stretch of oil pipeline that ran through the southern Baghdad neighborhood of Dawra. Heavily armed and lightly supervised, some members of the largely Sunni brigade transformed themselves into a death squad, cooperating with insurgents and executing government collaborators, Iraqi officials say.
“They were killing innocent people, anyone who was affiliated with the government,” said Hassan Thuwaini, the director of the Iraqi Oil Ministry’s protection force.
Here.