A London man has been sentenced to seven years in prison for terrorism offenses after an investigation that started with a complaint about a Facebook message.

Mohammed Kamal Hussain was sentenced in Kingston Crown Court Monday after being found guilty of encouraging terrorism and supporting a banned organization.

The investigation started when a man emailed the Home Office after receiving a private message on Facebook urging him to join the Islamic State extremist group. Police found that the 28-year-old Hussain sent that message and had posted numerous messages praising IS.

The person who notified the Home Office did not live in Britain and said he did not know the sender of the message.

The case was given to the Met Police’s counter-terrorism unit that specializes in removing online extremist material.

(AP)