"Who's Jack the Ripper?" a drunk shouted. "Who is he?"

Mist hung over Whitechapel Road like a dirty wet washcloth. A chill wind swept garbage from dispersing fruit vendors past the ankles of assembled tourists.They, too, wondered who terrified London with his brutal killings of five prostitutes in squalid East London on dark nights in 1888.

One hundred years later, all the cases remain unsolved.

Guide Mike Lermer said only he knew - and to learn Jack the Ripper's identity the gathered 100 would have to follow him for two hours through the streets where the Ripper killed.

Ripperology is thriving in this centenary year. More Ripper books have been added to the dozens already on the shelf. British and American television showed a miniseries that purported to reveal the true killer's name. T-shirts, postcards and other grim memorabilia mark Jack's anniversary.

And Lermer, 34, founder of the tour company Streets of London, has increased his "Jack the Ripper" walks.

"Why are people still so fascinated with the Ripper 100 years later?" asked Lermer, a serious figure with a penchant for the dramatic.

"Not because of the number of victims. He only killed five . . . the recent Yorkshire Ripper killed 13. It wasn't the brutality of the murders, although he killed in the most sadistic, barbaric way. It's simply because he was never caught."

First stop: London Hospital, where a century ago doctors examined a woman's kidney purportedly mailed by the Ripper.

With night pressing in, the group plunged into a foul-smelling narrow brick alleyway, across a bridge to Buck's Row, then lined with houses, today a parking lot in a gap left by a World War II bomb. Here the Ripper ritualistically slaughtered his first victim - Mary Ann "Polly" Nichols.

Instead of renting a bed the night of Aug. 31, Nichols spent the required four pennies on gin. It cost Nichols her life. Her head was nearly severed. Her abdomen was slashed.

Whitechapel and Spitalfields, where the Ripper committed his crimes, are the poorest parts of London, now as then. In 1888, 30,000 people lived in the streets and another 130,000 like Nichols were virtually homeless, renting beds or a stand-up sleeping spot for the night.

Jewish and Irish immigrants of a century ago have been replaced by Bangladeshis. Now the smell of curry blends with greasy fish and chips.

Dark-skinned children play in front of a Bangladeshi tandoori restaurant across Hanbury Street from where Annie Chapman's mutilated body was found Sept. 8, 1888. The site is now part of a brewery.

Lermer herded his group to The Ten Bells, a 1753 pub that was called "The Jack the Ripper" until a few months ago when a feminist group insisted the original name be restored. All five of the slain women drank at The Ten Bells, and all lived within 200 yards of each other, Lermer said.

Between a multistory car garage and a wholesale children's wear shop, the nearest one can get to the original Dorset Street site, Lermer describes the body of the Ripper's final victim, Mary Jane Kelly.

Kelly, at 25 the youngest of the five, was found early on Nov. 9, 1888, her face mutilated beyond recognition. With almost sadistic attention to detail, Lermer recounts the unspeakable mutilation of the rest of her body, so severe it took doctors six hours to piece together her body.

A short walk away on Goulston Street, a bloodied and torn piece of the apron of victim No. 4, Catherine Eddowes, was found. Written in chalk on a wall was: "The Juwes are the men that will not be blamed for nothing."

Eddowes was the second woman the Ripper killed the night of Sept. 30.

Elizabeth Stride fell first on Berner Street. Blood was still gushing out of her wound when she was found.

Police speculated that the Ripper was interrupted before he could mutilate Stride, and thus deprived he went in search of a second woman. He found Eddowes and left her savagely mutilated body a half-mile away in Mitre Square.

At the walk's end, Lermer reveals his conclusion about killer's identity: it was the queen's doctor, Sir William Gull, acting on orders of Prime Minister Robert Salisbury because the women were blackmailing the palace over a secret marriage and child between Prince Albert Victor and a shop clerk, Annie Crook.

Crook's friend Kelly had told other prostitutes about the union and they tried to extort money.

Lermer credits author Stephen Knight with the theory, long dissected and disputed by burgeoning Ripperologists. That hardly matters to the tourists who applaud and quickly scatter, suddenly reluctant to be out at night on the streets of London.