Both men face up to a 10-year prison sentence under the plea agreement. Judge William E. Smith scheduled sentencing for February.
Prosecutors said the men placed an ad in a Catholic newspaper that offered $2,000 to people who were terminally ill.
The pair lied to people who responded to the ads and got personal information that was then used to purchase bonds and annuities in their names without their consent, authorities said. They also lied to the companies issuing the accounts, prosecutors said, by falsely saying that the people opening the accounts had substantial wealth and investment experience.
Some of the terminally ill people were told accounts would be opened to benefit their families or to help others with a disease, but that didn't happen, prosecutors said.
Testimony began last week with a 2009 video deposition by a Westerly man who has since died of cancer. Richard Wiley said he had heard, while in hospice, about a philanthropist who was giving out money to help dying people with their expenses. He testified he met with Radhakrishnan, who gave him $3,000, had him sign some paperwork and turn over some personal information.
Prosecutors showed Wiley papers, bearing his signature, that authorized accounts be opened in his name, but he said he had given no such permission and didn't recognize some of the documents.