BOSTON (CBS) – A grand jury has indicted the estranged husband of Massachusetts State Sen. Stan Rosenberg on multiple charges including sexual assault and criminal lewdness.

Bryon Hefner has been under investigation since several men accused him of assault and harassment last year.

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Bryon Hefner and Stan Rosenberg. (WBZ-TV graphic)

Hefner, 30, was indicted Thursday by a grand jury on the following felony charges: five counts of indecent assault & battery on a person 14 or older; four counts of disseminating a visual image of a nude or partially nude person; and open and gross lewdness and lascivious behavior, according to the Suffolk County District Attorney’s Office.

He is scheduled to be arraigned in Suffolk Superior Court on April 24.

The scandal forced Rosenberg to step down as state Senate president.

“These are serious charges. They are now being handled by the judicial system. I have faith in that system and trust that it will adjudicate this case fairly,” Rosenberg, an Amherst Democrat, said in a statement Thursday.

In a statement, Massachusetts Senate President Harriette Chandler, D-Worcester, called the charges against Hefner “deeply disturbing.”

“These charges are deeply disturbing, and I thank the victims for their tremendous bravery in coming forward. Clearly, the actions described will not be tolerated, and the Senate will cooperate fully with the District Attorney and Attorney General’s Office,” Chandler said.

A spokeswoman for Gov. Charlie Baker issued a statement on his behalf.

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“Governor Baker and Lieutenant Governor Polito commend those who came forward to report these despicable actions and believe those who engage in crimes and sexual harassment of any kind must be held accountable,” said Lizzy Guyton, spokeswoman for Baker.

The indictments handed down Friday follow a joint investigation by the state Attorney General and the Suffolk County District Attorney.

Bryon Hefner. (Image Credit: YouTube)

The indictments allege that Hefner sexually assaulted one victim on three separate occasions in the Boston area, including once in June 2015 in a residential building and twice in April 2016, once in vehicle and once in a restaurant.

Hefner allegedly sexually assaulted another victim in 2014 and exposed his genitals to that victim in June 2016. The indictments allege Hefner sexually assaulted a third victim in August 2016. These alleged offenses happened in Boston.

Prosecutors allege that Hefner obtained nude and partially-nude photos of another victim without the victim’s knowledge and sent or showed those photos to four other people without the victim’s consent.

“This joint investigation revealed a disturbing pattern of conduct that was not only inappropriate but criminal,” Suffolk District Attorney Daniel F. Conley said in a statement. “No one, regardless of who they are or where they work, should have to endure the assaults and exploitation alleged in these indictments.”

“We see every day that disclosing sexual assault can be the most difficult thing many survivors ever do,” Conley said. “We know the facts specific to this case, with many of the parties working in politics and government, made it especially daunting for some to come forward. We will support them and protect their privacy to the greatest degree possible.”

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Hefner has since checked himself into a treatment center and has separated from Rosenberg.