CARL Williams' brain may be examined by scientists to analyse why he was a killer.

His ex wife, Roberta, has told New Idea magazine she has given permission for the examination for research into violent men.

"I believe it’s to help with research, and might explain why guys like Carl do the violent things they do, she said.

She also hopes the gangland kingpin didn’t suffer.

"Although the attack was reported to be very violent, I hope he died quickly so at least he didn’t suffer," she said.

"He’d have been brain dead before the cardiac arrest and wouldn’t have known about it.’’

Roberta is thought to be considering a lawsuit over her former husband’s death, which may have been linked to testimony he was going to give regarding a long-running investigation.

And she has denied considering having twins through artificial insemination with Williams or considering re-marrying him, claiming she was no longer in love with him.

Williams will be buried near his friend, hitman Benji Veniamin, whose gravesite is at Keilor Cemetery, on Friday.

Roberta has cited her concerns the funeral will become a circus, hiring six security guards to shield her daughters from unwanted attention.

She also revealed that he will be farewelled ironically with classic song Funny Face.

Originally published as Carl's brain donated to science