A 79-year-old New York accounting firm executive who worked for some of Bernard Madoff's most important clients is likely to receive leniency at his sentencing in return for government cooperation.

Paul Konigsberg is set for sentencing Thursday in Manhattan federal court after pleading guilty last year to conspiracy and falsifying books and records. He sold his Manhattan accounting and consulting firm four years ago.

Prosecutors agree he did not know about Madoff's epic fraud that cost thousands of investors nearly $20 billion. But they say he unwittingly helped it along by conspiring with Madoff employees to produce fraudulent investor statements.

Prosecutors recommended leniency, saying Konigsberg provided vital facts toward the prosecution of others.

The 77-year-old Madoff is serving a 150-year prison sentence after revealing the fraud in December 2008.