Gwinnett County District Attorney Danny Porter said Tuesday that he would not comment on any matter concerning a possible investigation of recent land purchases by the Gwinnett public school system.

Porter, the county's top criminal prosecutor, had mentioned in April that he was considering launching his own probe or seeking a grand-jury investigation. Doing nothing was "not viable," Porter said then. "I was hoping the school system would open their own investigation, but it looks like they are not willing to do that."

"I’m afraid I can’t discuss whether or not I am investigating a particular land purchase or purchases," he responded Tuesday in an email. "To publicly discuss any investigation or even acknowledge the existence of an investigation would hamper any efforts we were making."

The Gwinnett County school system came under criticism recently after published reports in the Atlanta Journal-Constitution showed that developers made large profits -- as much as $1 million in a day, in one case -- in recent land sales to the GCPS.

Since then, the GCPS has hired a former federal prosecutor to conduct a third-party investigation of all GCPS land deals since 1999. That probe, announced April 12, is expected to last six to eight weeks.

GCPS Superintendent J. Alvin Wilbanks has said that the system has saved $37.5 million on those deals, based on appraised prices. The published reports concerned deals made since 2004.

Also, the system is considering a revised policy for land acquisitions. The policy, which would require all purchases to be posted on the GCPS website and discussed at board meetings, was tabled at the May board meeting.