Mafia

"The Mafia" is a west coast criminal organization in Los Angeles allying with Mello. The group intends to posses a Death Note and thereby gain power. Mello's intellect becomes a useful addition to the group after Mello is able to find a rival gang. As a result, the Mafia's influence increases. How to Read 13 states that the organization is "being used by Mello."

The leader of the Mafia is Rod Ross, though Ross takes advice from Mello. Long-standing members Glen Humphreys and Rashual Bid are said

Rod Ross
Ross is the leader of the Mafia. His primary goal is to gain a Death Note and gain power, increasing the Mafia's influence.

Jack Neylon
Jack Neylon is a member of Mello's crew. He is the holder and user of Sidoh's Death Note after it is given to them by the Kira Task Force. Before Mello joined, Jack was involved with drug trafficking and illegal weapons sales; neither of which charge stuck due to lack of evidence, despite four separate arrests. After Sidoh tracks down his Death Note, Jack performs the trade for the Shinigami Eyes. Light uses the Death Note to have Jack mail him the address of Mello's hideout. In the anime, the eye trade and first raid attempt were cut.

Zakk Irius
Zakk Irius (his real name) is used by the Mafia to converse with the Japanese police at the airport. The organization kills Irius after he guides Soichiro to the correct aircraft. He dies by heart attack when the airplane lands; his crew wrote his name into the Death Note.

Glen Humphreys & Rashual Bid
Glen Humphreys and Rashual Bid are veteran gang members said to be the main force behind Ross. They are seen at the Mafia's hideout by satellite confirming its location, this behaviour was presumably manipulated with the Death Note by Light as an excuse for how he had discovered their true whereabouts (see Kal Snydar). They were killed by the Death Note during the raid by the Task Force members. Humphreys is known as Gurren Hangfreeze in the Japanese version and their real names are Ralph Bay & Al Meem respectively or Langford Bid & Yale Mison in Japanese.

Miller
Miller (real name Andrew Millar) is a member who was killed by "Y462" as a test subject as to whether the Death Note was real during the exchange. He was killed because he was stealing drugs from the gang to sell, and was described as an "incompetent guy".

Jose
Jose is not affected by the Death Note which kills the other members, as only his alias was known. He fakes being dead and fatally shoots Soichiro, then later dies when the rest of the Japanese Police enter the room and shoot him.

Roy & Skyer
Roy and Skyer are not affected by the Death Note, which kills the other members. They attempt to retrieve the Death Note, but the task force disarms and subdues them both, yet they later (presumably) die when Mello detonates the explosives which destroy the entire building. It's believed that ownership was transferred to one of them after Snydar died only to be lost upon their own deaths.

"Y462"
"Y462" (real name unknown), makes the exchange with Soichiro for the Death Note and is the one to kill Miller. He holds ownership of the notebook for a short time but is killed by a remote explosive planted in his helicopter after he loads the Death Note onto the missle. His death causes ownership to be passed onto the Kal Snydar, the first one to touch the notebook after he dies. Ross had falsely promised that making the exchange would redeem him of his past failures.

Unnamed Members
There are other unnamed members of the Mafia who are killed after the Mafia obtains a Death Note, due to Ross and Mello killing their underlings and subordinates, and leaving only a chosen few. Mello also has several Mafia members use the Death Note before Ross does in order to learn whether or not the 13 Day Rule is false.

Hideouts
The Mafia has several hideouts. A previous hideout that was used two years prior to the story is stated to be under SPK surveillance, following the Mafia's envolvment in the Kira case. The hideout that is first and primarily seen appears to be a factory or industrial plant of some sort, located in Los Angeles, California. The outside has several ladders and pipes on it, as well as a few staircases. This is the hideout that Sidoh arrives at in his search for his Death Note, as well as the first hideout to be raided by the Task Force.

The Mafia also has an underground bunker located in the desert. The bunker was used as the location to make a trade with Soichiro Yagami for the Death Note, in exchange for his daughter Sayu Yagami. The bunker appears to be a long tunnel-like structure. It has two openings; one which is used by Soichiro to enter and exit, and another which Sayu's kidnapper used to leave. Within the bunker is a revolving bullet proof door, used to exchange Sayu and the Death Note. The location also has a nearby base to launch a missle, which is used to transport the Death Note without being traced by radar.

Trivia

 * In the Rewrite 2 special, the mafia are omitted, with Light's meetings with Kiyomi Takada and Teru Mikami moved to earlier on, and them instead being the ones to kill the SPK.