The verdict was delivered by Judge Ravintharan N Paramaguru after 28 witnesses had given evidence since March last year.
Three other accused — Lie Chang Loon, Chin Wei Chung and Stephen Lee Chee Kiang — were earlier released and acquitted in June from the charge of being accomplices in the murder.
Fitri, the man accused of pulling the trigger in the mafia-style murder, was however ordered to enter his defence.
Kayong, 43, whose Muslim name was Mohd Hasbie Abdullah, was gunned down while seated in his Toyota Hilux vehicle about 8.30am on June 21, 2016, at a traffic light intersection at Lutong, near E-Mart supermarket in Jalan Miri-Bintulu.
The killing of the Miri PKR leader was believed to be linked to his work as an advocate of social issues, especially on indigenous rights and land issues.