An ISIS militant publicly executed his mother after she encouraged him to leave the radical Islamic State and flee with her, the UK-based Syrian Observatory for Human Rights reported on Friday.

Lena al-Qasem, 45, had told her son that a US-backed military alliance would destroy ISIS and tried to convince him to leave the Syrian city of Raqqa with her. He quickly informed on her, telling the militant group what she had said. ISIS detained her and ordered that she be killed.

According to the report, her son, Ali Saqr, 21, killed her on Wednesday outside the post office where she had worked in full view of hundreds of people.

Raqqa is an ISIS stronghold which has served as the Islamic State’s “capital” since the radical group captured the city in 2013.

The report is unconfirmed, though the incident was reported by two different organizations. However, one of them, called Raqqa is Being Slaughtered Silently (RIBSS), said that the woman was killed for the crime of apostasy.

Since the beginning of its reign in Syria and Iraq, ISIS has executed over 2,000 Syrian civilians accused of homosexuality, apostasy, and practicing magic. According to reports, ISIS has also killed a number of disabled children.