A Greenfields business owner and his son have been charged over the alleged assault of a would-be thief.
The man allegedly attempted to ram raid the Mower Magic store on Rouse Road with a stolen Isuzu ute around 7.20pm on April 3.
He then loaded a number of items into the ute.
During the incident the 38-year-old man was detained by the business owner and his son.
Police allege the men used excessive force to detain him, causing the man to receive serious injuries.
The alleged thief was taken to Peel Health Campus under a priority with head injuries before being transferred to Royal Perth Hospital.
The 49 and 29-year-old men from Stake Hill have jointly been charged with one count of grievous bodily harm.
They will appear in the Mandurah Magistrates Court on July 1.
A WA Police spokesperson said the injured man has recently been released from hospital.
Inquiries into why the man was at the business and his link to the stolen vehicle are now continuing.