New York - The former controller at Wall Street conman Bernard Madoff's investment firm pleaded guilty on Thursday to fraud and faces up to 10 years in jail for offences linked to his boss's gigantic Ponzi scheme.Irwin Lipkin, 74, also faces possible forfeiture of all his property when he is sentenced on March 22, the US prosecutor's office in New York said.Lipkin admitted securities fraud, falsifying records and making false filings to the Securities and Exchange Commission, the Wall Street regulator.He was a longtime employee of Madoff, but said he did not know his boss was running a giant fraud in which investors' deposits were siphoned off to pay phony dividends and attract new clients eager for the seemingly strong returns."Lipkin had a long history with Bernie Madoff, and he proved himself to be a loyal foot soldier - consistently and repeatedly breaking the law at his boss's behest, and leaving as his legacy a successor he personally taught to continue cooking the books," US Attorney Preet Bharara said."Lipkin was able to enrich himself and his family through fake trades, and no-show jobs during his tenure and thereafter," Bharara said."Today's guilty plea marks another step forward in our efforts to prosecute and punish anyone and everyone who we can prove participated in this breathtaking fraud."Madoff pleaded guilty to the multi-billion dollar scheme in 2009 and was sentenced to 150 years behind bars.