Philadelphia District Attorney Larry Krasner had promised his election would help spark "transformational change" within the D.A.'s office.
He started by dismissing 31 members from the office on Friday, three days after being sworn in, according to multiple reports.
Those asked to resign included trial attorneys and some supervisory staff, and the move could represent a 10 percent reduction in the number of prosecutors in the office, Philly.com reported.
The progressive Democrat and longtime civil rights defense attorney campaigned on pledges that included ending mass incarceration and mitigating prosecutions of minor drug cases. He also opposes the death penalty.
He also promised to overhaul the culture of an office marred by the corruption conviction of former D.A. Seth Williams, who was sentenced last October to five years in prison.
"This is a story about a movement," Krasner said after his election victory. "And this is a movement that is tired of seeing a system that has systematically picked on poor people – primarily black and brown poor people."
Philly.com reported that one assistant prosecutor let go was Andrew Notaristefano, who unsuccessfully sought the death penalty in a 1979 murder case. He reportedly secured 32 murder convictions in the last four years and had worked in the office for more than a decade.
He told the outlet that he requested to leave after prosecuting an upcoming murder trial, but was denied.
The office did not disclose reasons behind the individual firings, and some who lost their jobs told multiple media outlets that they were asked to leave without explanation.
In the weeks following his election, Krasner was reportedly granted permission by then-interim D.A. Kelley Hodge to allow his transition team to review the personnel files of hundreds of employees.
"People were freaking out," a source familiar with the process said in a BigTrial.net report on Dec. 12. "I think everybody's worried about being fired."