- This is one of the most famous letters in history.

- Wow.

- I'm showing this letter to a criminologist who works with violent offenders.

Is he convinced that this letter is really from the pen of the killer?

- "Dear boss, I keep on hearing the police have caught me, but they won't fix me just yet.

I have laughed where they look so clever and talk about being on the right track.

I am down on whores and I shan't quit ripping them till I do get buckled."

- Hang on, that's so powerful.

"I am down on whores," he says.

What the writer's doing here is giving us something that this case did not have, which is a motive.

"I'm down on whores."

- In my own work, one of the things that people ask all the time, why did they do it?

That the assumption is that the individual had some issue with prostitutes.

"My knife's so nice and sharp, I want to get to work right away if I get a chance, good luck.

Yours truly, Jack the Ripper."

- Jack the Ripper, the first time in history, those words appear.

- Yep, he wants to say, yeah, I'm probably walking around you.

I'm there, you can see me all the time.

But actually nobody knew who he was.

- What do you think the significance of the red ink is, Martin?

- It's quite simple.

It becomes symbolic of blood.

There's a line here, it says, "I saved some of the proper red stuff in a ginger beer bottle."

- That means the blood from the supposed killing.

- Yeah, but my thing is, if you mutilated someone in the way that the autopsy reports are, I'd like to know how do you suddenly stop and scrape a lot of blood or a vial of blood into it says a ginger beer bottle to write with, but it went thick like glue and I can't use it.

Well, even if it was glutenous, if it was fairly, you'd still be able to write with it, depends on the implement you use it.

- So you think this description of what the killer is supposed to have done, it doesn't stack up, it doesn't ring true to you as something that would've really happened.

Putting blood into a ginger beer bottle with a plan to write a letter with it later.

- In terms of my work, having worked with people who have done horrendous things, what tends to happen is when the crime happens, the emotional impact of witnessing what they've done has significant impact.

They don't satirize what they've done because if you really wanna tell somebody you've killed someone, you don't have to really go out your way to write it in red.

- True.

- Unless you are going to make a point with it.

- Do you think it's a bit odd that they've sent it to the Central News Office rather than the police?

- Of course they do, because you and I both know the moment you send a letter to a newspaper boss and they read it, they're just looking at sales.

So the moment you get this, you're thinking, I can make a lot out of this.

And then the police will start thinking, well, how come we didn't know about this first?

That still happens to this day.

It is like fake news.

So whoever did this knew that they were gonna generate publicity, they knew.

- You think the letter is basically a fake?

- Writers are very, very good at fabricating the truth to make you believe it.

And we are looking at this retrospectively, but I should imagine they could get away with it because there wasn't the forensic awareness to be able to prove it, 'cause if they did, we wouldn't be sitting there talking about it now.

- What are the repercussions?

- This is a very, very clever way to fuel the kind of obsession with dangerous individuals we get caught up in, who is it?

What did they look like?

When we look at crime fiction, we love the bad person.

Actors love the bad person, everybody loves the bad person.

If you presented the reality about what victims went through as a society, we'd have to respond differently to that act.

(dramatic music)