Mayor Ed Murray's search committee announced Friday that the list now includes police chiefs Robert Lehner from Elk Gove, California, and Frank Milstead of Mesa, Arizona.
Former Boston police commissioner Kathleen O'Toole is also a finalist.
Murray says he'll announce his nominee to the City Council by mid-May. He'll interview the finalists in the next few weeks.
The mayor's handling of the police department is being scrutinized after he appointed interim chief Harry Bailey, who proceeded to reverse misconduct findings against seven officers.
The department also has a reform agreement with the Department of Justice after federal investigators in 2011 found that officers too often escalate situations unnecessarily, sometimes resulting in the use of force.