Spitzer was the initial target of the investigation and was tracked using court-ordered wiretaps that appear to have recorded him arranging for a prostitute to meet him at a Washington hotel in mid-February, the official said.

The official spoke to The Associated Press condition of anonymity because of the sensitivity of the investigation.

The scandal surrounding the man who built his political reputation on rooting out corruption stunned the state. Calls for Spitzer's resignation began immediately and intensified Tuesday with the New York Daily News, New York Post and Newsday all demanding that he step down.

Spitzer retreated from public view Monday afternoon, when he appeared glassy-eyed with his shellshocked wife, Silda, at his side and apologized to his family and the public, but did not directly acknowledge any involvement with the prostitute.