Encased in a gold casket, Sam "The Punisher" Abdulrahim has been farewelled by mourners, as detectives plead for his family and friends to cooperate with their murder investigation.

Abdulrahim, 32, previously survived at least half a dozen attempts on his life, but on Monday his luck ran out and he was slain in broad daylight in a Preston hotel car park in Melbourne's northeast in front of his girlfriend.

The service for the bikie-turned-boxer was held at Alawi Islamic Association on Thursday morning.

"Taken too soon, Sam was a man full of life, he was loved by all and his smile would always light up the room," his funeral notice read.

"A loving father, son, brother, uncle, nephew, cousin, partner and friend. He will be dearly missed, but never forgotten."

Following the service, the coffin was draped in a green cloth and placed back in a hearse to be driven to Northern Memorial Park for burial.

The road near the service was closed for a procession led by a portrait of Abdulrahim, followed by motorbikes, four men carrying flower arrangements that spelt out the nickname "Suna", and the hearse.

Police were parked across the road, keeping watch, and Homicide Detective Dean Thomas reiterated officers were being mindful and respectful of the families, friends and loved ones dealing with grief.

"I respect that the funeral is today, but to Sam's family, friends and associates, I ask that they work with us and provide us with any information they have so that we can identify those responsible," Det Insp Thomas said on Thursday.