The New Zealander's two-decade deception has sparked urgent checks in Britain - with 3000 foreign doctors to have their credentials investigated.
Alemi, 56, claimed to have a degree from the University of Auckland when she came to work in the UK in 1992.
In reality, the convicted fraudster had flunked her first year and dropped out.
But nobody at the General Medical Council, the watchdog responsible for vetting the background of medics, checked whether her documentation was genuine.
Alemi, 56, is said to have provided a Bachelor of Medicine and a Bachelor of Surgery certificate from the university when she arrived in the UK in the early 1990s.
A spokeswoman for the university told the Herald Alemi was awarded a Bachelor of Human Biology on May 5, 1992.
She also started a medical degree - but did not complete it, the university said.
At that time, doctors from certain Commonwealth countries could be cleared to start work simply by presenting their qualifications, without sitting any assessments.
Alemi held a degree in human biology.
For the next 22 years, starting in 1995, she worked as a psychiatrist for the UK's National Health Service - treating thousands of mental health patients over that period and potentially earning up to £100,000 ($188,000) a year.
She also reportedly drove a Lotus Elise sports car.
Alemi's patients told to contact their GP
In a since deleted profile, Alemi says of herself: "I am a retired psychiatrist and a member of the London Royal College of Psychiatrists with a special interest in developmental conditions such as Asperger's ...''
The GMC is now informing anyone who was treated by Alemi at a GP surgery, hospital or clinic to get in touch with their GP.
Chief executive for the council, Charlie Massey, said staff immediately brought the situation to the attention of police and other agencies - including health authorities - when they discovered Alemi's fraudulent qualification.
She worked as a doctor up until June of last year.
"Our processes are far stronger now, with rigorous testing in place to ensure those joining the register are fit to work in the UK.
"It is clear that in this case the steps taken in the 1990s were inadequate and we apologise for any risk arising to patients as a result.
"We are confident that, 23 years on, our systems are robust and would identify any fraudulent attempt to join the medical register."
Alemi 'obsessed with money': former PA
Meanwhile, Alemi's former personal assistant says she repeatedly tried to raise concerns about her "bizarre" actions - but was ignored.
Claire Wilkinson worked with the bogus psychiatrist in Plymouth in 2014 and 2015.
She told Plymouth Live that Alemi was obsessed with money.
"She was very money driven; she lived for money. She would only find the wealthy men attractive - even if they weren't attractive.
"She went for wealth and hierarchy."
Wilkinson had also questioned Alemi's medical knowledge and her behaviour towards patients.
Alemi had refused to write prescriptions and even offered "electrotherapy" treatment to a young girl who was having problems with life at home, Plymouth Live reported.
"The first thing she said to me when she first met me was 'are your eyelashes real?'
"I had just met this woman and she was asking me things like that."
Wilkinson said she raised concerns with her line manager and a senior employee but nothing was done.
'Despicable' attempt to steal elderly woman's fortune
A judge described her as "despicable'' when she was sentenced last month, the Daily Mail reported.
Alemi was last month found guilty of four fraud and theft charges after a week-long trial at Carlisle Crown Court.
The New Zealander met Gillian Belham, now aged 87, at a dementia clinic in Workington in February 2016.
Within four months she had redrafted Belham's will - and fraudulently applied for power of attorney.
Belham's extended family and a raft of charities were "entirely written out" of the bogus will.
Instead, Belham's assets were to be held in a trust for the benefit of Alemi's grandchildren.
Judge James Adkin said Alemi's offending was "wicked''.
"This was despicable, cruel criminality motivated by pure greed and you must be severely punished for it."
Alemi had received warning over careless driving
Patients' groups called for a public inquiry as police confirmed their investigation into Alemi was ongoing.
John Woodcock, independent MP for Barrow and Furness, in the Lake District - where Alemi was most recently working - said the case was "hugely alarming".
"If this had been one individual that had slipped through the net it would have been concerning, but the idea that it could be a systemic loophole that has been exploited is hugely alarming," he said.
"It is understandable that patients are calling for an inquiry – this is of sufficient magnitude that that may well be necessary."
The General Medical Council admitted its checks had been inadequate and confirmed an "urgent investigation" was looking into the backgrounds of 3000 doctors who came to work from Commonwealth countries, before 2003, in the same way.
Incredibly, Alemi had been investigated and given an official warning by the Medical Practitioners Tribunal Service in 2012 after failing to disclose a conviction for careless driving.
