Gerald Morton Shirtcliff, aka William Anthony Fisher, is already facing an investigation by New Zealand police.
Now, an internal probe by professional engineering body Engineers Australia has found that the Brisbane-based Shirtcliff falsely assumed the identity, including a University of Sheffield engineering degree, of former colleague William Anthony Fisher. The matter will be looked at by the Australian Federal Police.
Engineers Australia has also cancelled Shirtcliff's membership.
"As soon as the allegations surfaced, Engineers Australia commenced an internal investigation," said chief executive officer Stephen Durkin.
"This investigation has provided evidence to suggest this member had misrepresented his engineering qualifications."
The 67-year-old was given a chance to respond to the allegations, but had not done so, Mr Durkin said.
Shirtcliff first hit the headlines this year when he initially refused to give evidence at the royal commission of inquiry into the collapse of the six-storey CTV building, killing 115 people, in the February 2011 Christchurch earthquake.
He finally fronted up after it emerged he was a convicted fraudster, having been jailed in 2005 for a GST fraud in which he falsified the books of a failing business he sold to a Queenstown couple.
During the hearing, he was accused by commission lawyers of distancing himself from responsibility after he claimed limited involvement in its construction, despite being construction manager on the project.
He told the hearing he was a graduate civil engineer. Asked why he lived in Australia under the Fisher identity, he said it was because of "family issues" going back 40 years.
Since giving evidence, he has been accused of stealing the identity of William Fisher, with whom he worked in South Africa, and faking an engineering degree to get jobs in New Zealand and Australia.
It is alleged the fake degree from Sheffield University gave him entry to a masters programme at the University of New South Wales in 1971, which led to his getting a master of engineering science in highway engineering.
The university is investigating Shirtcliff's background and says if the claims are proved, it will cancel his degree.
Yesterday, a spokeswoman told APNZ their inquiries were ongoing.
Shirtcliff's contract with global engineering consultancy WorleyParsons ended last month. The firm said a review of projects he worked on had found no irregularities.
He has continually denied any wrongdoing, mainly through his Brisbane lawyer David Tucker.
But Engineers Australia, which has more than 100,000 members, has moved quickly to cancel Shirtcliff's membership, which it said it can do under its by-laws, granted under Royal Charter.
Now, due to the "seriousness" of the case, Engineers Australia say they will also refer it to the Australian Federal Police for investigation.
Mr Durkin said: "Our members are held to a very high standard and Engineers Australia is committed to protecting standards in the profession and working with local authorities, state and federal governments to ensure these high standards are upheld."
Last week, it emerged Shirtcliff was being investigated by New Zealand police.
A police spokeswoman yesterday said: "Police received a complaint about Mr Shirtcliff, and a senior investigator has been assigned to the assess the allegations. This is all we can say at this time."
Building and Construction Minister Maurice Williamson has said Shirtcliff could face extradition to New Zealand and could face criminal charges if the allegations stack up.
