When Bernard L. Madoff entered a federal courtroom in Manhattan on Thursday to admit that he had run a vast Ponzi scheme that robbed thousands of investors of their life savings, he was as elegantly dressed as ever. But, preparing for jail, he wore no wedding ring  only the shadowy imprint remained of one he has worn for nearly 50 years.

He admitted his guilt for the first time in public, and apologized to his victims, dozens of whom were squeezed into the courtroom benches behind him, before being handcuffed and led away to jail to await sentencing.

“I knew what I was doing was wrong, indeed criminal,” he said. “When I began the Ponzi scheme, I believed it would end shortly and I would be able to extricate myself and my clients.”

But finding an exit “proved difficult, and ultimately impossible,” he continued, stumbling slightly in his prepared remarks. “As the years went by I realized this day, and my arrest, would inevitably come.”