It appears that Bruce Ivins, the main suspect in the anthrax case, was suffering from some kind of mental disease. He worked at the Army's biodefense lab in Fort Detrick, Maryland and committed suicide on July 29 by taking an acetaminophen overdose.

He is highly probable to be responsible for the 2001 anthrax mailings. There was indeed plenty of substantial evidence against him. He had access to the anthrax strain in the letters and might have had reasons to send them to members of Congress and several people from the media.

Bruce Ivins also had a fixation for Dr. Nancy L. Haigwood, 56, who now directs the Oregon National Primate Research Center in Portland. The microbiologist claims she was stalked by Ivins for several years being obsessed with the Kappa Kappa Gamma sorority she joined in college. The two met in the late 1970s when he was doing a postdoctoral fellowship at the University of North Carolina. She earned her doctorate there as well.

She moved to in a townhouse in the Washington, D.C. together with her fiancée in 1982. Her spouse to be found the Greek letters "KKG" spray-painted on the rear window of his car and on the sidewalk and fence in front of their home one morning. And now Dr. Haigwood is sure they were made by Ivins who secretly moved nearby at that time.

"My address wasn't published, and I only lived there a short while before Carl and I got married and moved out of state," Haigwood said Friday. "No one knew my address or my phone number. You had to stalk me to figure this stuff out."

Between 2000 and 2006 he was prescribed antidepressants.