Which preposition to use with abetters

of Occurrences 2%

In this respect, the Medici, and their abetters of the fifteenth century, discharged a portion of the debt which they had incurred to humanity.

in Occurrences 1%

It is really too bad, that the Primate of Ireland, of all men living, should be made the abetter in two fallacies.

Which preposition to use with  abetters