There has been no major Western publisher release for Zekka . The book's publication in Japan was met with massive public backlash, as the killer did not notify the victims' families beforehand and profited from his crimes.
: Sometimes, official manga or book websites offer downloads or links to their content. If "Zekka" is a well-known series, the author's official website or the publisher's website might have what you're looking for. zekka book english translation pdf link
While a direct PDF link to an official translation does not exist, here are the available ways to access the content: There has been no major Western publisher release for Zekka