Philadelphia District Attorney Larry Krasner on Tuesday replaced the chief of the Homicide Unit in his office and tapped a veteran city prosecutor to take over on an interim basis.

Chesley Lightsey, who has been an assistant district attorney for 12 years, will head the office formerly led by Anthony Voci, who has been the top homicide prosecutor since Krasner took office in 2018..

“I am humbled by the opportunity to help lead the Homicide and Non-Fatal Shooting Unit at what is a trying time for so many in our city,” Lightsey said.

“We face enormous challenges in policing and prosecution during this pandemic, including the fact that the court system is operating at a fraction of its capacity," she added. "Too many people are losing their lives or being harmed by senseless gun violence in Philadelphia and in nearly all major U.S. cities.”

Voci said he could not comment on why he was replaced.

The change in leadership comes at a time when homicide cases are surging and shootings are on the rise across the city.

Krasner spokesperson Jane Roh said the move was not related to the increase in homicides. Asked whether the move represented a demotion for Voci, she declined to comment. Roh also declined to say whether Krasner’s decision to replace Voci was related to an off-duty incident in September in which Voci, riding his motorcycle, clashed with a motorist he said tried to run him off the road.

Voci said he followed the driver, got her license plate, and called the police. The driver, Khasandra Franklin, 24, was initially charged with aggravated assault, a felony, but that charge was dropped the next day along with lesser charges of possession of an instrument of crime, simple assault, tampering with evidence, and obstruction of justice, according to court records. She is still facing charges of recklessly endangering another person and reckless driving.

Franklin and her passenger have said Voci called them “Black bitches” during the encounter. Voci, 57, has denied that.

In announcing the change in leadership Tuesday, Krasner’s office said he traditionally has appointed all unit supervisors on an interim basis. Going forward, the statement said, the office will continue to rotate experienced attorneys in and out of supervisory positions.

Lightsey, a native of Mississippi, earned a bachelor of arts degree from the University of Mississippi and a law degree from the Temple University Beasley School of Law.

Krasner called Lightsey “an excellent and capable trial prosecutor" with "thoughtful compassion for the communities we serve.”

Staff writer Chris Palmer contributed to this article.