NEW YORK — The brother of imprisoned financier Bernard Madoff was sentenced Thursday to 10 years in prison for crimes committed in the shadow of his notorious sibling, by a judge who said she disbelieved his claims that he did not know about the epic fraud.
Peter Madoff, 67, agreed to serve the maximum sentence allowable to the charges of conspiracy and falsifying the books and records of an investment adviser that he pleaded guilty to in June.
US District Judge Laura Taylor Swain urged him to tell the truth even after he reports to prison on Feb. 6 about what he knows about the multidecade fraud that cost thousands of investors their original $20 billion investment.
The judge said Peter Madoff was ‘‘frankly not believable’’ when he claimed at his plea that he only learned about the fraud when his brother revealed it to him just before he surrendered to authorities.
Peter Madoff spoke only briefly before he was sentenced, saying: ‘‘I am deeply ashamed of my conduct and have tried to atone by pleading guilty and have agreed to forfeit all of my present and future assets.’’
He added: ‘‘I am profoundly sorry that my failures let many people down, including my loved ones.’’
The sentencing comes four years and a week after Bernard Madoff revealed the fraud, which occurred over several decades as the former Nasdaq chairman built a reputation for delivering unparalleled investment results, even in bad times.
The revelation came only days after the business sent out statements that made investors think their investments had grown to a total of more than $65 billion.
Peter Madoff said at his plea that he had no idea his brother was running a massive Ponzi scheme, paying off longtime investors at times with money from newer investors.
‘‘My family was torn apart as a result of my brother’s atrocious conduct,’’ he said. ‘‘I was reviled by strangers as well as friends who assumed that I knew about the Ponzi scheme.’’
But he conceded that he followed his brother’s instructions and helped him decide which favored friends, clients, and family members would receive the $300 million that remained in the company’s accounts. The checks were never sent.
Peter Madoff, who joined his brother’s firm after graduating from Fordham Law School in 1970, has been free on $5 million bail after he agreed to surrender all of his assets.
Prior to sentencing, his lawyer, John Wing, said in a memorandum that Peter Madoff will ‘‘almost certainly live out his remaining days as a jobless pariah, in or out of prison.’’
Wing called his client a victim of his loyalty to his brother, saying he had been mistreated by the sibling who was eight years older and was viewed as ‘‘the prince’’ by their mother.
As part of a forfeiture agreement, Madoff’s wife, Marion, and daughter Shana must forfeit nearly all of their assets.