Bernard Madoff's former director of operations for investments has been sentenced to 10 years in prison.
Sixty-seven-year-old Daniel Bonventre was sentenced on Monday in federal court in New York for his part in the company's years-long multi-billion-dollar fraud.
Four other defendants are expected to learn their fate in coming days.
The government has said they're the most culpable defendants after Madoff for a fraud that cost thousands of investors nearly $US20 billion ($A22 billion).
In court papers, the government said their crimes involved ongoing and systematic deception.
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For years, they repeatedly lied to investors, regulators, auditors and banks.
Madoff was arrested in December 2008. He is serving a 150-year prison sentence.
