FLEMINGTON -- Four corrections officers at New Jersey's only women's prison were indicted last week over claims they sexually abused inmates, Hunterdon County Prosecutor Anthony Kearns announced on Monday.

At least eight inmates at the Edna Mahan Correctional Facility for women were abused by the officers over a period of two years, the prosecutor alleged at a press conference at the Superior Courthouse in Hunterdon County.

"In these cases, the victims were particularly vulnerable as inmates," Kearns told reporters. "The corrections officers had complete power and control over every aspect of their lives behind bars."

The indictments were handed up by a Hunterdon County grand jury on January 19, authorities said.

The indicted officers include Brian Y. Ambroise, 33, and Thomas Seguine, 34, against whom the prosecutor's office publicly announced charges last year.

They also include two others, Jason Mays, 43, and Ahnwar Dixon, 38, whose arrests had not been previously disclosed publicly.

All four men have been released on bail, authorities said. They could not immediately be reached for comment and it wasn't clear whether they had retained attorneys.

The prosecutor would not say whether any of the cases were related, but said there appeared to be "some crossover" between the defendants and some of their victims.

Kearns also announced that a fifth man, civilian employee Joel Herscap, had been sentenced to three years in state prison after pleading guilty to official misconduct charges related to claims of sexual abuse last fall.

The prosecutor said the charges were part of an "ongoing investigation" his office was conducting into sexual abuse at the Union Township facility.

According to the state Department of Corrections, six employees were fired last year over claims of sexual abuse, five of them from Edna Mahan. That came after several years in which the department reported no cases of sexual abuse behind bars.

In a statement, Commissioner Gary Lanigan said prisoners and their families "have every reason to trust" that inmates are "appropriately treated" behind bars.

"Violators of that trust should not and will not be taken lightly," he said.

Mays, of Hillside, was indicted on five counts of official misconduct, one count of a pattern of misconduct and three counts of sexual assault.

Dixon, of East Orange, was indicted on two counts of official misconduct, one count of a pattern of misconduct and one count of sexual assault.

Ambroise, of Union, and Seguine, of Philipsburg, were each indicted on one count of official misconduct and sexual assault.

S.P. Sullivan may be reached at ssullivan@njadvancemedia.com. Follow him on Twitter. Find NJ.com on Facebook.