A former Crown prosecutor once thought worthy to be considered for the role of Victoria's chief magistrate now faces a prison sentence after admitting indecent assaults on two teenage brothers that began about 30 years ago.

Magistrate Simon Cooper's crash to disgrace continued on Tuesday in Melbourne Magistrates Court where he had prosecuted and sentenced offenders for crimes similar to those he has committed, which carry a maximum five-year term.

Guilty plea: Simon Cooper is set to resign as a magistrate after admitting indecent assaults on two teenage brothers Credit:Michael Clayton-Jones

Cooper, 56, pleaded guilty to seven charges of indecent assault, including six on one boy, between 1984 and 1986. Six charges of attempted rape were struck out.

Fairfax Media has learnt he will now resign as a magistrate after being suspended since charges were brought against him in January.