A watchdog group is demanding Fulton County's top prosecutor step aside from the criminal investigation of the Atlanta Public Schools test cheating scandal. District Attorney Paul Howard's wife, who was not named in the investigation, works at a school where staffers are accused of altering answers to improve test scores.

The Fulton County Taxpayer Foundation, which launched a campaign this week to pressure Howard to issue indictments, now fears he is too close to the school system. His wife, Petrina Howard, is a counselor at M. Agnes Jones Elementary.

Howard said in a statement he will not recuse himself. Five staffers are investigating whether the scandal warrants criminal charges, he said. If the investigation uncovers any conflicts of interest, Howard said he will seek guidance from the state Attorney General's Office.

Attorney General Sam Olens said Howard had no obligation to step aside unless his wife became an investigative target or a witness.

"I am committed to the task of getting to the bottom of this scandal," Howard said. "I believe that the size and experience of my office make it uniquely qualified to complete an investigation of this magnitude with both integrity and professionalism."

Petrina Howard was a proctor during the testing and was interviewed in March by investigators whose report named 180 educators, including 38 principals as participants in cheating, said Michael Bowers, a lead investigator and a former state attorney general.

More than 80 APS employees confessed to cheating, according to the report. The investigators said they uncovered evidence of cheating in 44 of 56 schools they examined.

Legal ethicist David Zarfes said Howard probably isn't obligated to recuse himself when his wife is a minor employee in a large school system. Her employment, however, could give the appearance of a conflict and breed public suspicion, said Zarfes, an associate dean at the University of Chicago law school.

Petrina Howard's role was minor, Bowers said.

"Mr. Howard has been a stand-up and straightforward guy with us," he said.