In testimony to the US Senate judiciary committee, Andrew Adams, who leads the department's KleptoCapture task force, said Congress should let prosecutors seek forfeiture of assets used to evade US sanctions, not just the proceeds of sanctions evasions.
The task force was launched in March to enhance the US's ability to punish wealthy Russians who Washington accuses of enabling Russian President Vladimir Putin to invade Ukraine.
Prosecutors have since won warrants to seize two luxury yachts belonging to sanctioned Russians and planes owned by billionaire Roman Abramovich, among other assets.
Mr Adams said the task force could have done more with enhanced powers.
“I am aware of instances in the past where, had these provisions been in place, there would have been opportunities to take even more aggressive action,” he said.
Mr Adams urged Congress to let prosecutors charge people accused of breaching sanctions or export controls with racketeering.
The racketeering law, enacted in 1970 in the fight against the Mafia, allows prosecutors to charge a group of people, even those indirectly involved in alleged wrongdoing, for taking part in a “criminal enterprise”.
Mr Adams also said statutes of limitations for some financial crimes, such as money laundering, should be doubled to 10 years to give prosecutors “time to follow the money”.
Congress is considering legislation to allow proceeds from seized assets to help the people of Ukraine.
The Kremlin calls its actions in the country a “special military operation”.
Before seized assets can be liquidated, prosecutors must win permanent forfeiture orders, through often-lengthy court proceedings.