Mr. Caramadre has since tried to change his plea, and maintains that it was Mr. Radhakrishnan, not him, who lied to patients, but Judge Smith denied his motion to do so and said on Monday that it was “an incredibly cynical effort to manipulate the court” that had lengthened his sentence by at least a year.

The case has raised questions about the life insurance industry’s increasingly complicated financial products. It has also presented the court with a vexing picture of insurance companies whose own rules seemed to enable Mr. Caramadre’s scheme and of victims who gained money even as they sustained emotional and psychological losses.

“All of the terminally ill individuals actually made money — that makes it very unusual,” said Judge Smith, from the bench. But he reflected later that the scheme treated dying people like commodities. “In a way,” he said, “isn’t that worse than stealing money from them?”

Government prosecutors requested that Mr. Caramadre be sentenced to serve 10 years in prison, which was the maximum amount allowed under the plea agreement.

Judge Smith said the six-year sentence, to be followed by three years of supervised release during which Mr. Caramadre is to perform community service with the elderly and terminally ill, is intended to deter similar crimes while allowing Mr. Caramadre to get out of jail with enough working years to make a dent in his restitution obligations, which will be determined at a later date.

He also said it took into account Mr. Caramadre’s contributions to his community, which were detailed in 89 letters written to ask for leniency. In his letter, the bishop of Providence, Thomas J. Tobin, cited Mr. Caramadre’s philanthropy and personal involvement in church projects.

“In trying to make a positive contribution to our community, Mr. Caramadre has provided a good example for other leaders to follow,” Bishop Tobin wrote. “Experience tells me, your honor, that it is possible for good people to do bad things, and that the imposition of justice should consider the entire picture.”