Mahmud began his military career as an non-commissioned officer and rose through the ranks, becoming part of Hussein's personal bodyguard, and finally, his personal secretary.
A distant cousin of Hussein, observers regarded Mahmud as being Hussein's right hand man, in constant contact with him and acting as a gatekeeper to access to the leader: he was trusted. With Saddam's son Qusay Hussein, he headed the Iraqi Special Security Organization.
He was designated ace of diamonds in the US administrations most-wanted Iraqi playing cards and fourth on the most-wanted list after Saddam and his sons Uday and Qusay.