A little story about this book with an unsolved mystery of my own: I first came across "Portrait of a Killer: Jack the Ripper, Case Closed" when a coworker purchased it on a long flight from Phoenix back to Connecticut. We had an hour stopover in Las Vegas and the stewardess neglected to tell us to take our belongings off the plane so it could be cleaned. The book was left behind-it disappeared when we returned to our seats.
A few years later, I saw the book at a bookstore and my interest was piqued. I'd reviewed true crime books about serial killers before and learned that, unfortunately, serial killers can be horribly predictable. The problem is that the people around them willfully ignore the signs. So it was only a matter of time before someone applied the latest in forensic principles to the most famous serial killer in history.
Cornwell doesn't mince words: Walter Sickert is the killer (you can find this out if you turn the first page of the book, so no, it's really not a spoiler). The book is less a true crime mystery than a non-stop attack on Sickert-physically, socially, mentally, philosophically, and artistically. And he's an excellent candidate too; Sickert was fascinated with Jack the Ripper, painted creepy art that involved threatening and dismembering women, and traveled in all the right places where Jack the Ripper skulked. So he must be the Ripper, right?
Well, not quite. Although Cornwell makes a convincing case, the book is almost entirely dedicated to proving she's right...as opposed to finding out who the Ripper is. Sometimes, it's ridiculously over the top: Cornwell refers to Sickert as guilty, never allowing even the possibility that she might be wrong. Sometimes, it's insidious: Cornwell often glosses over discrepancies that other historians have unearthed. It's easy to start thinking Sickert's the Ripper when Cornwell refers to "his murders."
By the end of book, Cornwell paints Sickert as a supervillain of comic book proportions. If Cornwell is right, Sickert was the ultimate bogeyman. He could forge multiple handwriting styles at will, knew the ins and outs of every back alley, killed with calculated precision, was a master of disguise, and lied with incredible aplomb. "From Hell" was great, but I'd love to see "Portrait of a Killer" as a movie if only to experience the sheer audacity of an artist who dismembers his victims and then turns them into works of art.
That said, Cornwell provides an absorbing look at the life and times of the era in which the Ripper thrived and a compelling insight as to why the system failed. She bounces from modern forensics to Scotland Yard, drawing eerie parallels across a wide variety of fields: handwriting analysis, DNA analysis, and psychology. We learn most of all about the Ripper's (notice I didn't say "Sickert's") victims; in that regard "Portrait of a Killer" is an important contribution to helping readers understand Ripper through who he killed and where he lived.
The biggest flaw in Portrait of a Killer is that it really is "case closed." Cornwell's work hands down a verdict before any evidence is presented, making the whole book an entertaining but ultimately flawed argument about who Jack the Ripper really was.