A federal grand jury in Manhattan is investigating the sale of tax shelters by KPMG to corporations and wealthy individuals who used them to escape at least $1.4 billion in federal taxes, reported The New York Times.

From 1997 through 2001, KPMG collected $124 million in fees for tax shelters, according to a November estimate by minority staff of the Senate Permanent Investigations subcommittee cited by the Times.

Last month KPMG announced a new team for its tax service division, not long after several executives left the practice.

So far, despite widening scrutiny by Congress and the Internal Revenue Service in the face lawsuits by clients whose shelters failed, no subpoenas have been issued, which would indicate that the inquiry is in its early stages. Whether the investigation will focus only on the tax professionals and bankers involved in the design, sale, and execution of the tax strategies, or if it will include customers who bought the shelters, is unclear, said the Times.

George Ledwith, a senior KPMG spokesman, said in a statement that “it is our understanding that the investigation is related to tax strategies that are no longer offered by the firm.” He added that “KPMG has taken strong actions as part of our ongoing consideration of the firm’s tax practices and procedures, including leadership changes announced last month and numerous changes in our risk management and review processes.”

Marvin Smilon, a spokesman for David Kelley, the interim United States attorney in New York, declined to comment for the Times article.