Ahmad, 39, was shot dead on the street at Greenacre at 9.30pm on April 27 in what detectives described as another brazen and callous chapter in Sydney's ongoing gang wars.
Police on Tuesday arrested a 37-year-old they say was involved in planning Ahmad's killing.
The investigation is part of ongoing inquiries by Task Force Erebus into 14 fatal shootings and criminal activities by organised crime networks across Sydney.
A 49-year-old man remains before the courts after being charged last month both with being an accessory before the fact to Ahmad's murder and an accessory after the fact.
Detectives on Tuesday arrested the 37-year-old at a home at Fairfield East and charged him with being an accessory after the fact to murder.
He is also accused of knowingly or recklessly helping a criminal group with a crime, supplying a large commercial quantity of a prohibited drug and possessing a prohibited drug.
He was refused bail to appear at Fairfield Local Court on Wednesday.
Ahmad was slain six months after being released from jail after serving five years for the manslaughter of gangland rival Safwan Charbaji.
He had been warned by police his underworld enemies had placed a $1 million bounty on his head.
His brother and crime kingpin Walid "Wally" Ahmad also died in a hail of bullets while sitting at an outdoor cafe at Bankstown in 2016.
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