Mafia

The Mafia is an American west coast criminal organization allying with Mello. The group intends to possess a Death Note and thereby gain tremendous power.

Plot
Mello intends to beat Near and catch Kira, but needs a Death Note to do so. He joins the Mafia led by Rod Ross, who wants to increase the Mafia's influence. By allying together, Mello profits from the Mafia's resources and Rod Ross profits from Mello's intellect. Having proved his usefulness by killing a rival gang leader 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 notebook 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 to send it 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.

Mello subsequently instructs Sidoh to guard outside the base should there be any attackers, and this proves useful when Sidoh removes the helmets of attackers led by Yitzak Ghazanin, allowing Jack to write in all their names, using the Shinigami Eyes.

After this incident, the mafia switches bases. Kira hands over the notebook to the Task Force and instructs them to raid the mafia base, with him managing to learn the address by controlling multiple members of the mafia to mail him the address. The cue for the Task Force to attack is the deaths of the majority of the mafiosi, including Rod Ross, only for more deaths to occur from the attack.

Mello eventually has no choice but to blow up the base, most likely killing any few remaining members.

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 Japanese 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 bulletproof 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.

Trivia

 * In the Rewrite 2 special, the Mafia is omitted. With Light's meetings with Kiyomi Takada and Teru Mikami moved to earlier on in the story, they are the ones used to kill the SPK.