ALBANY -- The state Ethics Commission will investigate the scandal in which top aides to Gov. Eliot Spitzer used state police in a plot to discredit Republican Senate leader Joseph Bruno, according to a letter obtained by The Associated Press.

The letter dated Thursday says the state Ethics Commission, which has subpoena power, will investigate the case that has dominated the Albany agenda since an investigative report was released Monday by state Attorney General Andrew Cuomo.

The letter was provided by a state official on the condition of anonymity because the investigation hadn't been officially announced. When told of the letter, state Ethics Commission spokesman Walter Ayres confirmed it came from the investigative agency.

The commission seeks all interview transcripts, notes, e-mail and other material from Cuomo's investigation, but it can compel testimony under oath. Cuomo's interviews were voluntary because he lacked subpoena power in this case.

Cuomo's report released Monday concluded that Spitzer's Communications Director, Darren Dopp, and William Howard, assistant deputy for public safety, compiled and created records with the direct involvement of the acting superintendent of state police to show Bruno used state aircraft on days he attended Republican fundraisers in New York City. Dopp and Howard planned to release the records to a reporter, the report concluded.

Neither Dopp nor Secretary to the Governor Rich Baum, mentioned in the report as receiving e-mails from Dopp and Howard, gave testimony to the attorney general.

The letter was written the same day Spitzer, a former prosecutor, in a news conference refused to say whether it was appropriate that his top aides failed to fully cooperate with investigators looking into their use of state police against Bruno.

"I was not involved" in the decision, Spitzer said at a raucous news conference. He said he knew of the request that the aides testify. Spitzer has repeatedly denied knowing about the plot to discredit Bruno, the state's top Republican.

On Sunday, the day before the report was issued and after the Cuomo investigation was largely completed, Baum and Dopp submitted sworn statements through the governor's counsel's office.

Spitzer, the former crime-busting attorney general who made international headlines as the "Sheriff of Wall Street," defended the decision not to provide testimony.

He said Thursday that it wasn't necessary for Baum and Dopp to be questioned after Cuomo determined no crime was committed.

Baum, in an interview Thursday, said the decision was consistent with policy.

"The Attorney General's Office asked the counsel's office for testimony from me, and I guess form Darren Dopp," Baum said. "In general, the counsel's office frowns on sworn testimony of people in the executive chamber who advise the governor because they prefer to not have wide reaching questions about the advice to the governor."

"It was all done through counsel's office," Baum said.

Read the full report in Friday's edition of The Citizen.