Victims of Bernard Madoff’s record rip-off are crying foul at prosecutors’ plans to seek “extraordinary” leniency for the fraudster’s right-hand man.

In a series of outraged letters filed this morning in Manhattan federal court, burned investors are demanding harsh punishment for Frank DiPascali Jr., who pleaded guilty last year and is assisting with the ongoing probe of Madoff’s $65 billion Ponzi scheme.

“Cooperation with prosecutors does not convert this ignoble criminal, whose actions have harmed members of my family in this generation, the next and the one after that, into a man who deserves your mercy or compassion,” victim Ann Altman wrote.

Another victim, Robert Jacobson, urged “the strongest sentence allowable under law,” saying: “This is not vengeance but merely a hope that it may serve notice to other conspirators in financial scams that their misdeeds will not be treated lightly despite any assistance they may render to authorities.”

DiPascali, Madoff’s former CFO, faces 125 years in the slammer for his role in the scam, but prosecutors have said they expect to file an “extraordinary letter” seeking leniency due to the “substantial assistance” he has provided.

Information from DiPascali — who’s being held on $10 million bail — was cited in recent criminal complaints against three of Madoff’s other alleged accomplices.

A spokeswoman for the Manhattan U.S. Attorney’s Office declined comment.