After NBR brought the email to Mr Feeley's attention, investigations by PwC revealed no such email was sent by Mr Feeley or came from the SFO.
"While there was not actual evidence to prove Ms Killeen forwarded the forged composite email, by the process of deduction it certainly appears it was sent by her to the press," the judge said.
Of the decision to discharge, Mr Feeley said: "We have a legal system but not a justice system. I've just had a description of how proceedings unfolded and her not having to sit in the dock. These are not pleasantries normally afforded to people who commit crime.
"I'm not impressed with the outcome but quite frankly, I've long since moved on."
The judge cited evidence from Professor Ian Holdaway, senior consultant endocrinologist at Auckland Hospital, who said Killeen's psychological changes were a result of taking a double dose of the fertility drug.
Clinical psychologist Dr Julian Reeves also submitted that Killeen's bizarre behaviour was consistent with the medication.
The judge described how Killeen's culpability was at the lowest end of the scale and outlined how in 2010 the SFO was undergoing an organisational restructuring, initiated and implemented by Mr Feeley.
That abolished Killeen's role as chief prosecutor so she began personal grievance proceedings.
By last June, Killeen was appointed to the legal aid tribunal and to City Chambers as a barrister, and on the basis of specialist medical advice, she began taking a 50mg daily dose of the fertility drug clomiphene citrate. A practice nurse advised her to double to 100mg a day in November.
"It was during this period of time that a false email was created," the judge said.
"The implications were that the restructuring review had been predetermined and that was unfair and prejudicial to staff made redundant," the judge said.
"The offending had the capacity to completely undermine and diminish his [Mr Feeley's] standing in the community, staff of the Serious Fraud Office and Government," the judge said.
So he began an investigation to ascertain how the emails had come to the media's attention.
"Ms Killeen had no recall of the events in question. She experienced severe psychological reactions which led to a lack of awareness of what she was doing which led to impulsivity and a subsequent lack of recall," the judge said.
"Her abnormal behaviour was noted by her husband who noted obsessions with the SFO events - which they had put behind them - and loss of train of thought. "
Testimonials were presented about her.
"I have never seen a bundle of testimonials like these," the judge said. "This is an exceptional case and Ms Killeen is an exceptional person."
Fiona Cleary for the prosecution did not oppose the discharge without conviction or the judge's decision that Killeen make no compensation.
A Law Society spokesman said when a lawyer was charged in court it was likely a standards committee would investigate whether acceptable conduct had been breached. The case could be referred to a Ministry of Justice disciplinary tribunal.
