It looks like they are seeking to seize the bulk of his and his wife’s assets through civil forfeiture:

The government said in a court filing yesterday that it intends to seize assets including the Madoffs’ $7 million Upper East Side apartment in Manhattan and homes in Montauk, New York, Palm Beach, Florida, and France. Prosecutors will also seek $17 million in cash and $45 million in bonds in accounts in Ruth Madoff’s name, Acting Manhattan U.S. Attorney Lev Dassin said.

Ruth Madoff was Bernie Madoff’s bookkeeper for 3 decades, and her assets were at one point or another his assets: he transferred them to her to protect them, so this action is appropriate.

Note that they are going after what appears to be everything, including the piano and silverware.

It’s all proceeds of a criminal activity, and it will serve to deter people like Mr. Madoff if they know that transfer of assets will not protect his family.