The police have launched a full-scale investigation in Chung Sun-sin, the disgraced appointee for head of the National Office of Investigation, on suspicions that he intentionally hid his son’s school violence lawsuit during the vetting process.

The Seodaemun Police Station on Thursday summoned the head of a civic group on public welfare, Kim Soon-hwan, who made the allegations against the former prosecutor who resigned amid public outcry over his son's record of school bullying.

The civic group filed a complaint last month against Chung on charges of falsifying official documents and obstructing public affairs.

Chung resigned just a day ahead of assuming his post after it was belatedly revealed that his son had verbally abused a high school peer so severely that he was asked by the school to transfer.

Chung proceeded to sue the school in a case that went all the way to the Supreme Court, which ruled against him.