Monika Horna-Cieślak's office was searched by the Central Anticorruption Bureau (CBA) on Tuesday.
The District Prosecutor’s Office in Szczecin, northwestern Poland, said the investigation concerns the suspected offences of exceeding official powers and making a false accusation.
The investigation was opened on October 2 and is being conducted by the Szczecin Provincial Police under the supervision of prosecutors.
Julia Szozda, a prosecutor and spokeswoman for the Szczecin District Prosecutor’s Office, said the CBA search had been ordered as part of legal assistance and was intended to secure items that could provide evidence in the case.
The case follows a notification submitted to the Szczecin prosecutor’s office concerning the possibility of a crime being committed by the commissioner.
'Clear signs of institutional violence'
The investigation concerns an intervention in Warsaw’s Białołęka district in August.
According to reports by Polish media, Horna-Cieślak was walking along a street when she saw a woman pulling her child and shouting at them.
The commissioner stepped in and then notified the police. According to the report, the authorities subsequently ordered the parents to leave their home and banned them from approaching their children. The couple’s two children, aged three and four, were placed in a childcare facility.
The family court later criticised the response, saying the actions taken could bear "clear signs of institutional violence" and that state authorities had responded in a manner "grossly disproportionate to the incident."
Horna-Cieślak rejected the allegations. She said she had acted within her powers and in the interests of the children’s safety.
She also said the family had previously been known to the authorities and had been subject, among other measures, to Poland’s "Blue Card" procedure, which is used in cases of suspected domestic violence.
The investigation is ongoing.