“The F.B.I. is coordinating with the Justice Department to see if any laws were broken in connection with those matters related to the I.R.S.,” Mr. Holder told reporters. “Those were, I think, as everyone can agree, if not criminal, they were certainly outrageous and unacceptable, but we are examining the facts to see if there were criminal violations.”

But a matter portrayed by the I.R.S. on Friday as a little-known operation conducted in Cincinnati, largely out of the sight of Washington officials, continued to sprawl. The report by the Treasury inspector general for tax administration offered new details on the scope and duration of the I.R.S. targeting effort.

Mismanagement at the agency allowed “inappropriate criteria” for the singling out of conservative groups to be developed and stay in place for more than 18 months, starting in 2010, the report said. That resulted in “substantial delays” for groups applying for tax-exempt status, either as 501(c)(4) or 501(c)(3) organizations, and it allowed unnecessary and intrusive information like donor lists to be gathered. I.R.S. officials told the inspector general that all donor information received was later destroyed.

Of the 296 applications the inspector general reviewed, 108 were approved, 28 were withdrawn by the applicants and 160 were still open, some pending for up to 1,138 days.

In a statement Tuesday night, the I.R.S. acknowledged that “inappropriate shortcuts were used to determine which cases may be engaging in political activities.” But it said the agency had a responsibility to make sure that such organizations did not engage in impermissible political actions, and that not just conservative groups were singled out. It also said that “there was no intent to hide this issue,” but that the agency had been awaiting the inspector general’s report.

The report said that senior I.R.S. officials told inspectors that no individual or organization outside the agency influenced the criteria used to single out Tea Party or other conservative groups.

But Congressional aides looking into the matter are not convinced. One notation in a 12-page timeline of events prepared by the inspector general stood out for exploration. On Aug. 4, 2011, officials at the I.R.S.’s rulings and agreement office met with the I.R.S.’s chief counsel “so that everyone would have the latest information on the issue,” according to the inspector general.