The lawyer grandson of chief Sydney Harbour bridge engineer John Bradfield will not be jailed for a $3 million fraud because he is gravely ill and "likely to die" within months, the District Court has ruled.

John Gordon Bradfield, 74, was at the centre of a drawn-out investigation and prosecution for misappropriating clients' and friends' money as part of pyramid-style scheme spanning 30 years from the late 1980s.

John Bradfield at his home in St Ives in 2009. Credit:James Brickwood

He lost $2.3 million of his own money in the scheme, the court heard.

The fraud squad launched an investigation into Bradfield in 2010 and the former suburban solicitor pleaded guilty on February 5 last year to 10 charges of making false statements and using false instruments to obtain money.