Almost two decades after her husband was killed when he opened a parcel bomb, Jane Bowen-Sutton is still learning about the circumstances of the horrific act.

Geoffrey Bowen died when he opened the parcel at the Adelaide office of the National Crime Authority (NCA) in March 1994.

"Just coping with Geoff's murder and having two young sons probably was all I could cope with [at the time]," Ms Bowen-Sutton said.

Now a new book about the bombing is filling in some of the gaps for her.

The NCA Bombing: A Mafia Murder? is written by Adelaide author Michael Madigan and traces a line from the bombing through the world of Italian-Australian organised crime.

It paints a stark picture of ruthless criminal gangs who controlled the lucrative marijuana trade in Australia in the 1970s and 80s and who, in part, created the need for a national police force to investigate their activities.

That force became known as the NCA and began having an impact as it made arrests and large cannabis crops were destroyed in South Australia, Western Australia and the Northern Territory.

Madigan outlines how the crime syndicates were linked with the notorious Ndrangheta, the Calabrian organised crime group.

"Ndrangheta has infiltrated the whole world. They own the cocaine market and are responsible for the death of a number of people in Australia, including Geoffrey Bowen," he said.

The author spent more than five years researching the book and said the NCA bombing was a "stain on the soul of Australia".

There is a $1 million reward for information about the bombing, but Madigan thinks it needs to be increased five-fold to convince reluctant witnesses to come forward.

The author sent the first copy of his book to Jane Bowen-Sutton when he received it.

She admitted it was not an easy read but said it was important for her to understand and know what her husband was up against.

Mike Sexton ABC TV