Former immigration chief Mary Anne Thompson's doctorate thesis disappeared "in a black hole" after being sent to the London School of Economics, her lawyer says.
Defence counsel Robert Lithgow was questioning the school's academic registrar, Simeon Underwood, via video link at a depositions hearing in Wellington District Court.
Thompson faces three fraud charges after applying for public service jobs in 1989, 1998 and 2004, claiming she had achieved her doctorate in philosophy.
Underwood had not met Thompson and, under questioning, relied on the school's records.
Mr Lithgow suggested he was attempting to put together a jigsaw which had some pieces missing.
Underwood said the record "seems to be full up to the point where Thompson submitted her thesis".
Prosecutor Grant Burston said yesterday the thesis had been sent for examination in 1990 but no degree was confirmed as Thompson had not undertaken the oral examination.
Underwood on Tuesday told the court he did not know where the documents were now.
Lithgow asked if it would be reasonable to describe the loss of a top level student's thesis as an embarrassment.
"I wouldn't share that judgment," Underwood said.
"Because the pieces of the jigsaw - as you said at the start - are missing."
He said there may be an explanation which was not made clear in the school's paperwork. Lithgow said Thompson would have had to travel from New Zealand to England for the oral exam. He asked whether there were circumstances under which the exam could be waived on extreme compassionate grounds.
Underwood had only heard of this being done once, "and that was posthumously".
He said there had been correspondence over whether Thompson could do her oral exam in Australia as her supervisor was due to visit Queensland.
Ultimately the supervisor was told they could not act as examiner, but it was not clear in the school records whether this was passed on to Thompson .
Two more witnesses from the school were due to give evidence via video link this week, with court sessions beginning early to accommodate the time difference.