Graffiti tag link to school chook killers

A graffiti tag that appears to say "Siko" is a lead in a police investigation into the killing of 14 pet chickens at a Perth primary school.

The principal and assistant principal of St Brigid's Primary School in Middle Swan were shocked to find the birds bashed to death earlier this week.

The RSPCA and WA Police are investigating the incident.

Police are seeking help from the public to identify the person who left a graffiti tag at the scene.

RSPCA spokesman Tim Mayne said a similar incident occurred at Calista Primary School in Kwinana last month.