Police said the New York City Medical Examiner's office would conduct an autopsy to confirm Madoff's cause of death.

It was the Madoff sons who alerted authorities in December 2008, after they said their father had confided the scheme was on the verge of collapse. Although the brothers consistently have maintained they were blameless, investigators have focused on them because they worked closely with their father in the family's financial businesses.

Flumenbaum suggested the continuing investigation might have triggered the suicide, saying Mark Madoff "succumbed to two years of unrelenting pressure from false accusations and innuendo."

"We are all deeply saddened by this shocking turn of events," said Flumenbaum.