Croatian law requires a parliamentary vote to approve any such decision by the prime minister, but in this instance it is likely to be a formality as the opposition has been calling for such action for a long time.
Local media have reported that Zvonimir Hodak, Ivana's father, was a lawyer for Vladimir Zagorec, a former Croat general, who was recently extradited from Austria on charges of embezzling more than $5m.
Monday's killing was the latest in a wave of brutal attacks in Zagreb since June. A journalist and two businessmen were targeted in three previous assaults, which police have described as attempted murders.
Sanader said his government "won't allow organised crime to make the impression that they can do whatever they want without sanctions".
"The government and all the institutions concerned will do everything to quickly find the authors of this abominable crime," he said.
"We are not going to give organised crime the idea that they can do what they want with impunity. We are committed to an unrelenting struggle against organised crime, against the mafia."