User blog comment:Martialmaniac/Illumi's necromancy/@comment-4828844-20151021095057

Illumi was hired by Chrollo to kill the Ten Dons. He rang the transmitter to inform Silva that he killed their clients first, therefore ensuring that Chrollo must be kept alive so that he could pay Illumi for the job.

I assume the Dons were killed and then controlled by Illumi, not turned into Needlemen. What other motives should Illumi have for keeping them his Needlemen? Spy into the Mafia association? Seems unlikely. He was hired to kill them after all.

In Chapter 102, perhaps Illumi did control the Ten Dons to cover the Troupe's background for Chrollo.