The federal government is expanding its crackdown on offshore tax evasion and preparing numerous criminal cases against suspected offenders.

It has been four years since the agreement between the United States and Switzerland pierced a veil of banking secrecy by requiring Swiss bank UBS to turn over names of account holders to the IRS. Currently, more than 100 criminal investigations may be under way against suspected tax evaders. The U.S. government already has won approximately 50 criminal cases and collected at least $5.5 billion in connection with undeclared offshore accounts.

Now the Department of Justice has announced in a Jan. 8, 2013, news release that Mary Estelle Curran, a 79-year-old widow, best known for her volunteer work, pleaded guilty to criminal charges of filing false tax returns and evading approximately $668,000 in federal tax on $40 million her husband left her in a secret Swiss bank account at UBS. She agreed to pay almost $22 million in penalties. Curran is scheduled to be sentenced next month. She faces up to six years in prison.

Many tax attorneys believe that the Department of Justice wants to send a message that no one is too old or too rich, too poor or too sympathetic, to escape criminal prosecution.