French newspaper Le Monde described it as "the robbery of the century" and an academic called it the "biggest tax theft in the history of Europe".
In all, more than 400 suspects and a number of banks and companies are being pursued by German officials.
Mora, who went to St Bede's College and Canterbury University, was described by the Times as a "beefy, 6-foot-2 New Zealander with an apparent fondness for Hawaiian shirts".
He met Shields, an Irish mathematician, at the London office of investment bank Merrill Lynch in 2004.
It was in that office where the Times said cum-ex trading appeared to have originated.
The trading, through a complicated series of transactions, allowed the trader to get two refunds for dividend tax on a single set of shares. Cum-ex traders insisted it was legal, but German authorities ruled in 2012 that it was against the law.
A German court has now ruled that it is a felony offence, meaning any convictions could lead to heavy penalties and jail terms.
Mora and Shields later moved to the London branch of a Munich-based bank, HypoVereinsbank. That bank was raided by German authorities, who reclaimed US$160 million in fines and repayments.
By then, the two men had already left and formed their own company, Ballance Capital, to focus on cum-ex trading.
The tax trades finally came to a halt when a clerk in a German tax office in Bonn uncovered tax refund applications in 2011 and reported them.
The Times said German authorities were looking to make an example of Shields, whose trial began in September.
Mora was indicted in December and will be tried in coming months, the newspaper said.
He is believed to be in New Zealand and has not appeared in German courts so far.
"If the Bonn trial ends in convictions, stiff penalties are expected," the Times article said.
Companies Office shows that Mora still has a number of business interests in New Zealand, and is listed as the director of several Christchurch-based companies.
