To know the chilling story of married British serial killers Fred and Rose West is to know one filled with macabre aspects, lies, and the murders of at least 12 young girls and women. It is also to know the divergence in the path, where the unraveling of their innocence led to an ongoing investigation and intense interest in the truth about these horrific crimes nearly 25 years later.

Journalist Howard Sounes, the host of the new podcast "UNHEARD: The Fred & Rose West Tapes," exclusively spoke to the International Business Times about about how his storytelling process has changed over the two decades, the mystery that still surrounds the case, and whether or not he thinks serial killers have any "human" aspects to them. 

In the late '80s and early '90s, the time before the ubiquitous watchful eye of smartphones and claustrophobic feeling of social media, Fred and Rose West lived a seemingly normal life in the middle of an English cathedral city. With shops and a police station surrounding their home at 25 Cromwell Street in Gloucester, England, the married couple lived a facade of normalcy for years.

The crimes that the duo were eventually convicted of, which will be extensively explored in the new podcast, were both gruesome and disturbing. They also left those who followed the case with a lot of questions.

"Why were so many body parts missing, when the police finally recovered the human remains? Every victim had missing bones. Where are these bones? No one knows. Who drove the crimes - Fred or Rose? People tend to assume it was Fred, but there is strong evidence that Rose was even more sadistic," Sounes told IBTImes as he reflected on the ever-changing narrative of the crimes "that still shock and fascinate."

From over 100 archived audio tapes and interviews that he originally used for his 1995 best-selling book "Fred & Rose," Sounes revisits the events in a new way, swapping out the written word for an audio exploration. The transition changed his storytelling and investigative process for a new audience.

"The voices of the interviewees drive the podcast, both archive recordings and new interviews. We let the witnesses tell the story as much as possible, and there is something very compelling about hearing these people talk, in gentle West Country English accents, about multiple murder," he said.

Additionally, he revealed that now, looking back decades later, he has a unique point of view having had the benefit of following the case for such an extended period of time. "I am more sensitive to the effect the case has had on many different lives, and I see how hard it is to get to the truth about these crimes, as the truth is obscured by lies and mythology created principally by Fred West himself."

But does Sounes believe that the couple had any "human" qualities even though they committed those horrific crimes? 

When asked, he replied, "Fred and Rose West are commonly described as evil monsters, but they were, of course, innocent children once, as sweet and blameless as any children. What changed them? As we hear in the 'Unheard' podcast, they were both raised in dysfunctional families where they were probably corrupted, possibly by their own parents. Secret child sexual abuse runs through the generations in this story, and it is that sexual abuse that escalated into murder with Fred and Rose."

Filled with what Sounes himself describes as "jaw dropping moments" and new interviews with the victims' families who are speaking for the first time, "UNHEARD: The Fred & Rose West Tapes" will examine "one of the most infamous serial murder stories in British history." 

As for what's next for the author, he has a new biographical book out in the U.S. this month, "The Life of Lou Reed: Notes from the Velvet Underground (Diversion Books)." He is also the author of other well-known biographies of Bob Dylan and the American writer Charles Bukowski. 

"UNHEARD: The Fred & Rose West Tapes" with Howard Sounes can be found on Apple Podcasts