He was the only person pulled off the bus by Taliban militants on September 20. His beaten body was found on the side of the road,the report said.
Ghazni's deputy governor,Mohammad Ali Ahmadi,told the ABC's AM program that Mr Musawi,who held an Australian passport,was killed because he was an Australian citizen.
"Of course the reason is that he was an Afghan-Australian,"he said.
"He didn't do anything besides that – he didn't do anything wrong,he wasn't a criminal,he wasn't involved in government activities.
"The reason of his murder was very clear – that he was a dual citizen,he came from a country that Taliban think is an infidel country.
"When the Taliban arrested him,he said to them,'I came from Australia to see my family.'And then the Taliban... issued an order for his murder."
Mr Ahmadi said Mr Musawi's hands were tied behind his back and there were signs of beating.