By Kevin Connolly
BBC News, Washington
The US authorities portrayed Ivins as an unstable and troubled character
Bruce Edwards Ivins was an enigmatic character who ended his life in much the same manner as he appears to have led it - a manner which was troubling, ambiguous and dark.
It is also impossible to construct a convincing and rounded picture of Ivins' personality from the conflicting impressions offered by FBI investigators on the one hand, who believe he was a deeply disturbed mass murderer, and on the other by friends and colleagues who portray a gentler, more reflective figure.
There are shades of light and dark within most of us, but rarely are they as extreme as the different facets of Ivins' character.
Here was a man who played the organ in his local church, founded a juggling group to entertain children and wrote amusing jingles to play at leaving parties when colleagues moved on to new jobs.
He was also tormented by paranoid, delusional thoughts, drank heavily and wrote a poem containing the lines: "I'm the other half of Bruce - when he lets me out... I push Bruce aside, then I'm free to run about!"
This all matters because the American authorities have taken the extraordinary step of publishing the evidence they had collected against Bruce Ivins.
They are trying to prove that he was solely responsible for the anthrax attacks in late 2001, which terrified an America already traumatised by the 9/11 bombings.
In effect we have heard the case for the prosecution against a suspect who will never be able to defend himself.
Anthrax was posted to politicians and media offices shortly after 9/11
The American people will play the role of jurors as the Federal authorities attempt to persuade them that this case is closed.
Whatever you think about the evidence, it is worth noting that the federal authorities have some difficult questions to answer in the case.
First, they have just paid $5.8m (£2.9m) to a previous suspect - Stephen Hatfill - who also worked as a government research science in the field of biological warfare, just like Bruce Ivins.
Now, the fact that the investigators were wrong once does not mean they are wrong every time, but the Hatfill affair means the prosecutor's case will be examined with particular care.
And of course there is the question of security at the Fort Detrick base where Ivins worked.
If he really was the unstable, heavy-drinking character now portrayed by the authorities, why did he have security clearance to work in such a secret and sensitive area of defence work?
He was working on anti anthrax vaccines used by American forces.
There is a good deal of circumstantial evidence against Bruce Ivins which he might have found difficult to explain in court.
He wrote emails before the anthrax attacks - we have not been told to whom they were sent - in which he set out dramatic warnings about how America's enemies had biological or chemical warfare agents and intended to use them.
Most people will reach verdicts guided by their general views on America's federal institutions
The wording of the letters that subsequently proved to contain anthrax were remarkably similar.
He was the sole custodian of a flask of the particular strain of anthrax used in the attacks; in the run-up to those attacks he began working late at night and alone and couldn't explain why; he misled investigators.
On the other hand there is very little direct evidence.
A trawl through his private emails found no admission of guilt. Anthrax was never found in his house.
The letters containing anthrax, which were posted to various political offices and news organisations, were sent from a post box in New Jersey.
No petrol station receipts or toll-booth tickets could be found to prove he had been there at the relevant times.
In fact here is a piece of evidence which sums up a prosecution case described by one American newspaper as "compelling, but not airtight".
The post box in question is a very short distance from an office used by a college sorority organisation called Kappa Kappa Gamma (KKG) - sororities are powerful institutions within American university life that provide social networks.
Ivins was said to have had a lifelong obsession with KKG because one of its members apparently rebuffed him when he asked for a date at college.
The location of the post box could be a coincidence of course, but it could be evidence that a man with a dark underside to his personality was playing out a lifelong grudge in some vague way even as he set out to terrorise his fellow Americans.
Reaching a verdict
We will never know how a jury would have evaluated that aspect of the case.
That is a pity because almost nothing in the story of Bruce Ivins' life and death can be taken at face value.
Some of the evidence about his state of mind, for example, came from a therapist providing follow-up counselling after one of Ivins' stints in a hospital dealing with addiction problems.
Mr Ivins' attorney said the casebook did not prove he carried out the attack
But some newspapers have reported that the therapist too had lived a troubled life - that does not devalue the testimony, of course, but such a witness might have had a difficult time in the witness box.
The defence might have argued that the Ivins family was placed under unbearable pressure by the authorities.
There have been stories - denied by prosecutors - that FBI agents even confronted Ivins in front of his wife and their children in a shopping mall.
In that reading of the case he might have taken his own life because he felt he was being hounded, rather than because he feared that his guilt was about to be exposed.
Most people will reach verdicts guided by their general views on America's federal institutions - if you are inclined to trust government agencies, then you will accept their view on Ivins' sole responsibility for these terrible crimes.
If you are not, you will probably be sceptical.
Mr Ivins' attorney said the casebook showed why he was a suspect, but did not prove he had done it.