A graduate of Cheverus High School in Portland and the University of Maine School of Law has been appointed by Gov. Paul LePage to serve as district attorney for one of the state’s largest prosecutorial districts.

Jonathan Liberman of West Bath was appointed Monday to be district attorney for Sagadahoc, Lincoln, Knox and Waldo counties, filling a vacancy left by the confirmation of Geoffrey Rushlau as a District Court judge.

Rushlau, a Republican who had been the district attorney since 1993, was nominated to the District Court by LePage earlier this year. He resigned Friday after being confirmed by the Maine Senate as a judge.

Liberman said he will complete Rushlau’s term, which expires in 2018. If Liberman wants to keep the job, he will have to run for election in November 2018.

Liberman, a Republican, has been the deputy district attorney under Rushlau since July. From May 2011 until 2016, Liberman was an assistant district attorney.

The governor’s press secretary, Adrienne Bennett, issued a statement saying that when a vacancy occurs for a district attorney, the political party to which the outgoing prosecutor belongs must submit replacement candidates to the governor, who makes the appointment.

The Republican committees for the four-county district met in April and nominated Liberman and Paul Cavanaugh of Woolwich to succeed Rushlau. Cavanaugh is deputy district attorney for Kennebec and Somerset counties.

After reviewing the backgrounds of both candidates, LePage selected Liberman on Monday to replace Rushlau, the second-longest serving district attorney in Maine.

Liberman has a bachelor’s degree in political science from Syracuse University.