Portland Deputy Police Chief William Ridge says he will retire at the end of this week to become a social studies teacher at Holy Cross Middle School.

Ridge's announcement comes as Portland begins its search for a new police chief following the departure of Tim Burton to become chief in Odessa, Texas.

Ridge, currently head of investigations, has been with the department 25 years and is eligible to retire and receive a portion of his salary.

The department's other deputy chief, Joseph Loughlin, is serving as interim chief until Burton's replacement is named by City Manager Joe Gray.

Ridge said he began taking the courses needed to get his teaching certificate a couple years ago and became eligible to retire in April. He has a bachelor's degree in political science and a master's in public policy, which he said should be helpful in teaching courses on government and civics.

His children attended Holy Cross, a South Portland parochial school, and he has served on the board of directors in the past, including as its president.

Ridge, 48, has taught at the college level previously, at St. Joseph's College, Southern Maine Community College and the Maine Criminal Justice Academy.