New Rebels bikie president Jamie Ginn has died suddenly at the Perth Watch House.
Gang Crime Squad detectives took the 50-year-old into custody in Gnangara around 1pm on Tuesday.
He was then taken to the Perth Watch House where he was charged with a number of drug and firearm offences.
Around 7pm, Ginn reportedly had a seizure inside his cell.
"Immediate medical assistance was provided until the arrival of St John WA, however, the man could not be revived," a WA Police spokesperson said.
"The death is not being treated as suspicious and as per standard protocol officers from the Major Crime Division will prepare a report for the Coroner."
Ginn's death comes less than a week after an alleged gangland shooting in Baldivis.
Two Rebels bikies have been charged over the alleged shooting that targeted Mongols bikie Adam Wragg.
City of Kwinana proposes 4.5 per cent rate rise
Recreational boat fishers offered $50 rebate for fishing gear at participating tackle shops
Waikiki teen among the best CrossFit athletes in the world
Mandurah's Kerrie Overell crowned WA Volunteer of the Year
Wellard home destroyed by fire
Woman fined $7k after catching 134 undersize crabs in Coodanup
Mandurah mayor Amber Kearns 'disappointed' in councillor Peter Rogers' decision to resign
Speed limit dropped to 70km/h on stretch of Mandurah Road in Secret Harbour
WA Police officer tragically dies in hospital days after Hopeland crash