Waheed Iqbal was found guilty of seven fraud-related charges after giving five overseas students false certificates when he was the principal of the London College of Computing and Management.
Three victims were given bogus degrees from Hertfordshire by Iqbal, one of whom tried to use the certificate to obtain a visa from the Home Office. Hertfordshire was unaware of the scam.
The government department discovered the fraud after noticing that the dean who signed the certificate had retired in 2003, explained Rhianne Trill, a Metropolitan Police officer who worked on the case.
Iqbal, 58, who was born in Pakistan and was living in Isleworth, Middlesex, was sentenced to two years and six months in prison after being found guilty by a jury at Blackfriars Crown Court in January.
PC Trill said that more of Iqbal's victims were now coming forward. Two other students were given certificates from the non-existent Liverpool Metropolitan University.
PC Trill said that the victims may have been "slightly naive", but added that the London College of Computing and Management had been officially recognised by the British Accreditation Council and had a website and "all the facilities".
She added that many students at the college had obtained other qualifications entirely legitimately.
The BAC stopped accrediting the college in 2009 after it found evidence that it was "no longer upholding the scheme's standards", according to Gina Hobson, the council's chief executive, who assisted the police with the investigation.
PC Trill said that there was "no reason for [the BAC] to doubt what Dr Iqbal was up to", adding that no university was aware of the scam before the police were alerted.
Iqbal was also a senior member of staff at the London College of Excellence.
He obtained a doctorate from Fairleigh Dickinson University in the US via distance learning.
Times Higher Education was unable to contact the London College of Computing and Management and the London College of Excellence. The police said that both institutions appeared to have closed down.