MANDURAH Detectives are investigation a series of robberies in Greenfields on Monday March 27 and Thursday March 30.
A man entered a retail store on the corner of Pinjarra and Lakes roads about 12pm on March 27.
The man stole numerous electrical items and exited the store.
A staff member followed the man and requested he return and pay for the items.
The man became aggressive and threatened the staff member before riding off on a bicycle with the items.
About an hour later, the same man entered a nearby retail store, selecting numerous electronic items and exiting the store.
A staff member approached the man and he became aggressive and threatened the staff member before riding off.
Several days later about 1.20pm, the same man entered a retail store at the same location.
Staff recognised the man and called police.
The man selected an item and began to leave the store.
Staff attempted to prevent him from leaving but he threatened them with a box cutter knife and left before police arrived
The man is described as light skinned, late 20s to mid 30s, 185cm tall, medium build, short light brown hair and clean shaven, with tattoos on his left upper and lower arm.
He was riding a black adult-sized mountain bike.
Detectives have released CCTV and images of a man who could assist police with the investigation.
Call Crime Stoppers on 1800 333 000 or report online.