Steven Kurtz's attorney called it a "colossal overreaction" and "complete circus" when hazmat-suited FBI agents from Quantico stormed the art history professor's home in Buffalo, N.Y., last month.

Kurtz had called 911 to summon help for his wife, who had stopped breathing, and rescue workers noticed vials and laboratory equipment in the couple's home. Kurtz explained that he used the materials in his art. Then federal agents swooped in, evicting Kurtz, quarantining his home and collecting bacteria cultures and books on chemical warfare.

Yesterday, after a seven-week grand jury investigation, federal prosecutors in Buffalo charged Kurtz with mail and wire fraud. Not bioterrorism, about which they had questioned Kurtz's colleagues at the State University of New York at Buffalo, but with fraudulently acquiring samples of difficult-to-obtain bacteria through the University of Pittsburgh.

An indictment released yesterday said Kurtz and Robert Ferrell, the head of the human genetics lab at Pitt, schemed to illegally procure two biological organisms for Kurtz to use in an art project. Prosecutors allege they defrauded the university and American Type Culture Collection, a biological supply company based here in Washington.

According to the indictment, Ferrell used his affiliation with the university to order samples of Serratia marcescens and Bacillus atrophaeus, which Kurtz wanted to use in a project for the Critical Art Ensemble, a group he founded with his wife, Hope, that is known for its protest and performance art. The artwork containing this bacteria was scheduled to be displayed in Massachusetts this month.

Assistant U.S. Attorney William J. Hochul Jr. said yesterday from New York that the problem was not so much that Kurtz and Ferrell got the bacteria, but how they did so.

"Mr. Ferrell and Mr. Kurtz set about defrauding by misrepresenting themselves . . . using false and fraudulent pretenses, that the materials were going one place when they were actually going another," he said. "I continue to defend any artist's rights to this day."

"That's subterfuge," countered Kurtz's attorney, Paul J. Cambria, also speaking by phone from New York. "It clearly impacts on his art, impacts on his free speech rights. You need a criminal intent to commit a crime. These acts were innocent."

In the indictment, prosecutors cited correspondence in which Kurtz and Ferrell discussed obtaining the bacteria, including an e-mail from Dec. 19, 2003, in which Kurtz wrote: "Hi Bob, Well it looks like my bacteria is not as harmless as I previously thought. While not wildly dangerous, it is associated with pneumonia and urinary tract infections, and seems to be around other infections as well. Seems to be hardest on kids and people with compromised immune systems. Do you know what kind of strain we are getting, and how toxic it is?"

On Jan. 12, Kurtz e-mailed Ferrell again: "Hi Bob, I got the package you sent today. Many thanks."

Kurtz's supporters decried the federal investigation as an attempt to squash free speech by confiscating the makings of art. Hope Kurtz, it was determined, died of a heart attack. If convicted on the fraud charges, the men face up to 20 years in prison.

Steven Kurtz, shown last month in Buffalo, was indicted yesterday on mail and wire fraud charges for obtaining bacteria allegedly by false pretenses.