Camden County Police Chief Scott Thomson didn’t understand when his mentor, former Philadelphia Police Commissioner Charles Ramsey, told him that it would be clear when it was time to leave the force.

After 25 years, Thomson, who oversaw the transition of the department from Camden City to county control in 2013, will retire at the end of August, Freeholder Director Louis Cappelli Jr. said Friday. Assistant Chief Joseph Wysocki will replace Thomson.

Thomson had been chief of the city police force since 2008, before the county took control of the department.

While the force is called the Camden County Police Department, its jurisdiction is limited to the long-troubled waterfront city.

Cappelli and others, including Ramsey, credited Thomson with overseeing a reduction of crime rates in Camden and efforts to build trust between the police and the citizens of the city.

Thomson said in a statement that he would remain involved in the city as a board member with Camden Sophisticated Sisters, which describes itself as a “life-saving” nonprofit “disguised as a drill team,” as well as a volunteer with Guadalupe Family Services and other organizations that help Camden’s youth.