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.

Plot
Mello intends to beat Near and catch Kira, but needs a Death Note to do so. He joins the Mafia which is led by Rodd Ross, who incidentally wants to increase the Mafia's influence. By allying together, Mello profits from the Mafia's resources and Ross profits from Mello's intellect. Having proved his usefulness by finding a rival gang that "even Kira couldn't catch", Mello becomes a primary member, with Ross taking Mello's advice.

They eventually get their hands on a Death Note by kidnapping Sayu Yagami, and asking for the Death Note in exchange for her life. At an underground bunker, they give Sayu to Soichiro Yagami, who hands over the Death Note. The notebook is then loaded onto a missile that cannot be tracked by radar, and is sent elsewhere. Having recovered the notebook, Mello orders the death of all but four members of the SPK.

Sidoh, who has been searching for his Death Note, eventually arrives at the Mafia's hideout. Sidoh identifies Jack Neylon as the current owner of his Death Note, and takes it out of Mello's hands before dropping it onto Neylon's head. Neylon becomes terrified upon seeing Sidoh, and tells everyone to touch the notebook. Upon doing so, the other members view Sidoh, and begin to shoot at him. The bullets do nothing, of course. Sidoh strikes up an alliance of sorts with Mello, who tells him that the two rules written in the back of the notebook are 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 involvement in the Kira case.

First Hideout
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.

Second Hideout
The second hideout is used after the previous one is raided by the Task Force. The hideout appears to be a large, Victorian-style building, furnished with seemingly expensive items. Many important events take place here. This hideout is raided by the Task Force, with Soichiro Yagami having the Shinigami Eyes. Nearly all members of the Mafia subsequently die, Soichiro is mortally shot, and Mello escapes being captured by setting off a large bomb.

Underground Bunker
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 missile, which the Mafia use to transport the Death Note without being traced by radar.

Rod Ross
Rod Ross is the head of the Mafia, though he primarily follows Mello's orders.

Jack Neylon
Jack Neylon is the primary owner of Sidoh's Death Note after it is given to them by the Japanese Task Force. 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 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 behavior was presumably manipulated with the Death Note by Light as an excuse for how he had discovered their true whereabouts. 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 missile. 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.

Pedro Kollet
Pedro Kollet (alias unknown) interrogated Takimura and in the custody of watching it but dozed a little and Takimura committed suicide.

Eddie
Eddie, with Pedro Kollet, also had to examine and monitor Takimura.

Ill Ratt
Ill Ratt is a SPK member passing the information obtained from the organization and went to the Mafia (more specifically to Mello).

Greg Parker
Greg Parker was in charge of buying the groceries of the group and was discovered by Mogi, for he had bought several bars of chocolate from the same brand.

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.

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.