Abdullah Bahsa was shot and killed in a targeted attack in Lidcombe, in Sydney's west, on March 16.
Strike Force Vanport detectives arrested seven men shortly after the shooting, but launched a public appeal last week seeking more information.
Following the appeal, police have now charged an additional four people, including a 23-year-old man in Oakhurst, a 24-year-old woman in Rosehill, a 19-year-old woman in Belrose, and a 20-year-old man in Kemps Creek.
Three have been charged with murder, while the 19-year-old woman has been charged with serving as an accessory after the fact.
In addition, the 23-year-old man and the 20-year-old man were both charged with wounding a person with intent to cause grievous bodily harm, while the 24-year-old woman was also charged with hindering an investigation.
All were refused bail.
News of the arrests comes after Mr Bahsa's sister Manal directly appealed to those involved in her brother's killing to come forward.
"I'd ask you to consult your own conscience. Imagine this was your family member, and you're sitting here today appealing to them," she said through tears at a police press conference on September 17.
"You know who you are, you know what you've done ... No matter how insignificant this information might seem to you, it might be just the piece of information that we need to to give Abdullah justice and to put an end and closure to our suffering."
She described her brother as a kind and generous man who looked after their mother.
"He had a family who loved him. He was a brother to me and a son to my mother, and we miss him very, very much," she said.
"His murder has left a very big gap in our lives."
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