HOLYOKE — A Chicopee woman killed in Holyoke early Sunday was a former legislative staff member who was currently employed as executive assistant to Hampden County Sheriff Nick Cocchi.

Authorities said Eileen Monaghan, 48, was stabbed by a man identified by the sheriff’s office as her boyfriend. Jason Chapdelaine, 52, of Springfield was charged with murder and was ordered held without the right to bail following his arraignment Tuesday in Holyoke District Court.

Chapdelaine, a firefighter with the Chicopee Fire Department, is now on unpaid leave, Mayor John Vieau’s spokesperson Chloe Soto said Tuesday.

Monaghan served as chief of staff to state Rep. Joseph Wagner of Chicopee before his retirement at the end of last term. Wagner in a statement Monday called her his “closest friend.”

U.S. Rep. Richard Neal was among those sharing his sadness at the news of her death, saying he’d known her family for many years.

“Eileen was a truly kind and intelligent person who dedicated her life to public service … My thoughts and prayers are with Eileen’s family and friends, especially her two daughters,” he said in a statement.

The slaying took place near the banks of the Connecticut River, according to the Hampden district attorney’s office, where Holyoke police responded to a 911 call Sunday and found Monaghan, who “appeared to be suffering from stab wounds,” and a man “unresponsive due to self-inflicted harm.”

The Hampden sheriff’s office said in a post Monday that “domestic violence” had claimed Monaghan’s life.

“Eileen, a mother of two young women, was brutally murdered in Holyoke this past weekend, allegedly at the hands of her boyfriend,” the office wrote.

Wagner, the House’s former second assistant majority leader, wrote on Facebook that Monaghan “was respected by her peers, and loved and admired by her family and large circle of friends … It is impossible in this moment to understand such a profound loss resulting from a senseless act of violence.”

House Speaker Ron Mariano said the news of Monaghan’s death was devastating.

“Eileen embodied everything that is best about public service: She was smart, hardworking, and committed to making her community a better place. Above all, she was incredibly kind and always put people before politics,” Mariano said.

Monaghan’s brother, Michael Monaghan Jr., died on April 4 after a battle with cancer, according to the sheriff’s office.

“Eileen was truly a rose in a world of thorns. As we try to process this tragic loss, please keep the Monaghan family in your thoughts and prayers,” Sheriff Cocchi wrote in a statement. “To say Eileen was loved and will be missed is an understatement.”

Staff writer James Pentland contributed to this report.