Perrin will spend the next 22 months in the Dochas Women's Centre after being sentenced on Wednesday for attempting to deceive pensioner Thomas Davis (83) out of half of his €1m estate.
Sources said that Nevin made the approach in the courtyard area outside one of the houses which make up the complex.
The meeting happened adjacent to Laurel House, which incorporates the medical unit where Perrin (61) is being held.
The Dochas has houses with "rooms" as distinct from cells.
It is understood that Nevin made a point of ensuring contact by crossing over from Maple House to greet Perrin.
The Laurel House area accommodates those tagged with a "dependency" rating for health or security reasons.
Maple, on the other hand, is a no dependency unit with very low security risk attached to prisoners.
The contact between the two women, reported to senior management, was seen as a welcome gesture coming amid fears for the former judge's security inside. Perrin, who has resigned from the bench, was a "visiting" judge in the Dublin District Court when Nevin successfully contested a charge of possessing a mobile phone. After their chat, the disgraced judge was observed walking in the area with a number of African inmates, some of whom committed "drug mule" offences.
"It is in the early stages but so far there has been no animosity towards the former judge," said a source.
"There seems to be a certain deference perhaps of because of her former position or her age and difficulty in walking."
This weekend Perrin will be getting used to life behind bars -- and no doubt struggling to adapt after sharing a home with her husband Albert in Lambay Court, Malahide.
It is likely that Perrin will have to share her cell with one other prisoner.
As yet there has been no indication of an appeal but she was visited yesterday by her solicitor.