The four applicants remaining in Seattle’s search for a new police chief hail from the states of Arizona, Massachusetts, and California.

Sources have identified the four finalists to KIRO Radio as:

Robert Lehner, Chief, Elk Grove Police Department

Lehner has 30 years of law enforcement experience and previously served as the police chief in Eugene, Ore., according to his biography. Prior to that, he served as an assistant police chief for the Tucson Police Department.

Read more about Chief Robert Lehner here.

Patrick Melvin, Chief, Salt River Police Department

Melvin served for 21 years on the Phoenix Police Department before retiring at the rank of commander, according to his biography. He went on to serve as police chief in Maricopa, Ariz.

Read more about Chief Patrick Melvin here.

Frank Milstead, Chief, Mesa Police Department

Milstead has led the Mesa Police Department since 2010, following a 25-year career with the Phoenix Police Department, according to his biography. Read more about Chief Frank Milstead here.

Kathleen O’Toole, former Police Commissioner, Boston Police Department

O’Toole began her career in law enforcement in Boston in 1979, according to her bio. She rose through the ranks to become Boston Police Commissioner in 2004. She currently heads a private consulting firm in Boston.

Read more about Kathleen O’Toole here.

Mayor Ed Murray expressed frustration at a press conference on Thursday after O’Toole’s name alone was leaked to the media and reported by The Seattle Times.

“When candidate’s names are leaked, or the fear of leaking happens, they drop out,” said Murray, who said one candidate had already done so before the field was narrowed to four. “Whoever is leaking this information is doing a disservice to this city.”

Murray said appointing a new police chief will be the most important decision he makes as mayor.

“Should a tragedy happen in this city, if we don’t have the right person, lives can be lost,” he said.

While Murray said releasing the names could impact the city’s search for a new chief, KIRO Radio decided to release the final three names so O’Toole was not subject to undue public scrutiny or attention while a decision is made.

In a statement shortly after KIRO Radio reported the names Friday, the mayor’s office confirmed the report and released statements from co-chairs of the search committee.

“We are very appreciative of the all the individuals who’ve expressed interest in becoming Seattle’s next chief of police – particularly of the four candidates whose names are now public,” said Ron Sims, former King County executive. “Each of the candidates identified thus far has the background, the skills and the commitment that Mayor Murray has articulated as critical attributes of the next chief of police – integrity, management experience, the ability to be a change agent and drive reform. All are highly regarded in their communities and each would make incredible contributions to ours.”

Seattle has had an interim police chief since the retirement of Chief John Diaz in April 2013. Assistant Chief Jim Pugel, now retired, was promoted to the interim role following the announcement, but was replaced by former-Assistant Chief Harry Bailey, who came out of retirement to accept the position in January.

Murray is expected to announce his choice for the next permanent chief in mid-May.