Story highlights Tatsuyuki Hishida was found tied up and bleeding, police say; autopsy shows he was beaten to death

Police say he was a boss in Japan's largest crime syndicate, which recently split into two factions

(CNN) A man described by police as a boss in Japan's organized crime network, the yakuza, was found dead on Sunday night, bleeding from the head after being bludgeoned multiple times, a police official told CNN.

Tatsuyuki Hishida was found bleeding from the head with multiple injuries, said police officer Yoshihiro Nakamura of the Mie Prefectural Police Organized Crime Division. He said Hishida's hands and feet were bound by plastic cable ties.

Hishida's wife and staff found him at the entrance area of his second home in Yokkaichi city of Mie prefecture in western Japan, according to his wife.

An autopsy showed Hishida died of traumatic shock from numerous blows all over his body, Nakamura said. An investigation into the slaying is underway.

Photos: New Zealand's most notorious gang Photos: New Zealand's most notorious gang These haunting portraits by photographer Jono Rotman offer a close look at the largest gang in New Zealand, the Mongrel Mob. After coordinating with a gang liaison, Rotman met mob members and gained unprecedented access to them. He took these portraits inside their homes from 2008 to 2014.

Hide Caption 1 of 7 Photos: New Zealand's most notorious gang The Mongrel Mob started in the 1960s. Its members are known for their extensive tattoos and for wearing an emblem of a British bulldog with a Nazi helmet on their jackets and helmets. Most members are predominantly Maori people, the indigenous population of New Zealand. Hide Caption 2 of 7 Photos: New Zealand's most notorious gang The Mob appropriated Nazi party symbolism as their own but they are not white supremacists, Rotman said. "That Nazi iconography is a firm part of their identity and it's got nothing to do with white supremacy," Rotman told CNN. "The fathers and grandfathers of a lot of those guys brought back war booty from fighting the Germans, so there were a lot of swastikas and Nazi helmets lying around in attics and basements." Hide Caption 3 of 7 Photos: New Zealand's most notorious gang One of Rotman's subjects shared his grandfather's reasoning for choosing the swastika. "(He told me,) 'You think you're the master race? Well, I'll take your skin and put it on. Now who is the master race?' " Hide Caption 4 of 7 Photos: New Zealand's most notorious gang The Mongrel Mob Portraits, which debuted at City Gallery in Wellington in 2014, were criticized for glorifying gang culture . The series included this picture of convicted killer Shane Harrison . "The uproar seems to be more about the idea that you're not allowed to show these people in a respectful way," Rotman said. "It's like they should only be shown in a gritty documentary or in police mug shots." Hide Caption 5 of 7 Photos: New Zealand's most notorious gang The New Zealand-born and San Francisco-based photographer says he didn't ask his subjects to pose. "Other than perhaps occasionally saying 'Face me directly' or 'Turn to the side a bit,' they tend to just sit how they are. It just so happens that they have a certain gravitas," Rotman said. "I haven't done makeup. I haven't done Photoshop. I've just taken a backdrop, a camera and photographed what existed." Hide Caption 6 of 7 Photos: New Zealand's most notorious gang After dedicating the last eight years to this project, Rotman wants viewers to know he was not attempting to spin a narrative. "It's not actually about the Mob," he says. "It's more an effort to present these people so that the images speak for themselves. It is for the faces to reveal stories about the person, rather than for me to translate their story, which is not mine to tell." Hide Caption 7 of 7

Police say Hishida was the head of one member group in Japan's largest crime syndicate, the Yamaguchi-gumi.