Police raided more than a dozen locations while investigating claims that the family of main opposition People Power Party(PPP) presidential candidate Yoon Suk Yeol's wife received preferential treatment in a development project.

Around 30 investigators from the Gyeonggi Nambu Provincial Police Agency began searching 16 locations Thursday morning.

Last month, a civic group filed a complaint against an unidentified official in charge of licensing at Yangpyeong County, Gyeonggi Province, for allegedly providing favors to a company owned by the mother-in-law’s family. The group also filed a complaint against the woman, surnamed Choi.

The allegations are in relation to a development project taken over by the private sector after the state-run Korea Land and Housing Corporation(LH) scrapped a public rental housing project in 2011.

The county is suspected of extending the company’s project authorization period from November 2014, when it was set to expire, to July 2016 without the company applying for the extension. It also allegedly waived development charges.

After the ruling Democratic Party brought forth the allegations, the Gyeonggi provincial government launched an internal audit in October, before requesting a police investigation against four county officials and Choi.