A bloody roadmap of America’s worst murders

The perfect crime rarely is.

Even the cleverest killer can slip up somewhere. A footprint in the flower bed, a fingerprint on a doorknob, a strand of hair by the body – something’s always left behind.

Adam Selzer’s “Murder Maps USA: Crime Scenes Revisited” details dozens of these stray clues, and the killers they helped catch.

Or didn’t. Not every real-life detective is a TV show, able to close every case. These crimes are revisited, not necessarily solved. Although Selzer details more than 75 years of murders, some cases remain ice cold.

Want to play detective? Examine accompanying forensic evidence — from bloody murder weapons to grisly crime-scene photos — and see if you can spot something the original cops didn’t.

Not that the police who first responded had it easy. Selzer’s book focuses on murders committed between 1865 and 1939. Laboring decades before DNA analysis and computer databases, investigators faced tough work without today’s technology.

“Criminology” wasn’t even a word until 1885, and some of the new science’s practitioners were outright quacks. Early textbooks “seem at best laughable, and at worst racist,” Selzer writes. “Great emphasis was put on physical features, and race” in identifying “criminal types.”

Still, scientific breakthroughs like fingerprints and ballistics helped push police work forward. They also helped polish the image of police officers, who were often slammed as lazy and corrupt.

“They have no respect for the law, and depend upon their pull with the alderman to get them out of trouble,” read a 1904 expose of the Chicago Police Department. “They sleep when they should be on their rounds. They play the slot machines and drink with anyone who asks them.”

Of course, bad cops – and their third-degree methods of obtaining confessions – would never vanish. But advances in forensics gave good cops better ways of solving crimes.

And in the violent era that “Crime Maps USA” chronicles, there were plenty of cases to close.

Sometimes, newspapers helped. On June 26, 1897, half of a headless torso was floating in New York’s East River. The next day, the other half turned up in the woods near 176th St. Days later, a pair of legs was found near the Brooklyn Navy Yard.

The head never did show up.

The top half of the torso still had its arms, and a reporter noticed something. He recently had a massage, and the corpse’s fingers looked familiar. On a hunch, the reporter began asking if any masseurs had gone missing lately. William Guldensuppe had.

Police questioned the masseur’s cheating girlfriend, who not only confessed but implicated her current lover. They shot Guldensuppe, then cut him up in the bathtub. She was sentenced to 15 years. Her boyfriend got the chair.

Cleveland cops had less luck with a similarly grotesque crime. On Sept. 23, 1935, two teenagers found a naked, chemically preserved body missing its head and genitals.

Another corpse in the same headless, sexless state was found a year before in Lake Erie. Over the next few years, at least 12 murders would be linked to the same killer.

Eventually, the police arrested a man named Frank Dolezal. They tortured a confession out of him and threw him in jail, awaiting trial – where he supposedly committed suicide.

But retired gangbuster Elliot Ness, then Cleveland’s director of public safety, wasn’t convinced. He suspected Dr. Francis Sweeney, a former specialist in battlefield amputations since sunk into mental illness and alcoholism. Sweeney failed two polygraph tests and later committed himself to a hospital. But he was never charged.

Some killers may have been just too clever for the police. Minnie Wallace was 15 when she met the much older James Walkup at her parents’ New Orleans boarding house. He immediately proposed and, after a months-long courtship, took her home to Emporia, Kan., where he was mayor.

Several months later, Walkup was dead — but not before telling doctors that his bride was poisoning him.

Minnie was arrested, and druggists testified she recently bought strychnine and arsenic. But her lawyers said she purchased them for Walkup, who needed them to treat his venereal disease. Minnie was acquitted and moved to Chicago, where she married yet another wealthy, older man.

“A man must know how to woo a woman to win me” she said, explaining her proclivity for wizened men. “And young men have not the experience.”

Two weeks after changing his will in her favor, her second husband died mysteriously, too. Minnie, who was never charged, drowned her sorrows by beginning a new romance, this time with a railroad baron.

Eventually hauled into court for unpaid attorney fees (which were settled out of court), she stayed true to form. Minnie met another rich old man, De Lancy Louderback who was so besotted he built her a modern mansion. She never lived there but moved to London and married someone else. Within days Louderback died of – yes, cyanide poisoning. She died a free woman, old and rich.

And some killers were too smart for their own good, like genuine geniuses Nathan Leopold and Richard Loeb. Leopold, a budding ornithologist, graduated from the University of Chicago at 19. Loeb earned his diploma from the University of Michigan at 17. Rich, spoiled, and cocky, the Chicago teens decided to prove their superiority by killing someone and getting away with it.

Smart as they were, they only got it half-right.

The killing part was easy, or so they thought. They abducted a 14-year-old neighbor, Bobby Franks, and hit him with a chisel, leaving his corpse by the train tracks. But they didn’t get away with it.

Two rookie mistakes? Leopold lost his glasses at the scene. And the fake ransom note they sent was traced to a typewriter stolen from Loeb’s old fraternity house.

Arrested, the two confessed quickly, each fingering the other as the actual killer.

Brilliant defense attorney Clarence Darrow managed to get them life sentences instead of the death penalty. Loeb died in prison, stabbed by another inmate. Leopold was eventually paroled after serving 33 years. He moved to Puerto Rico and wrote a book about native birds. He kept a framed photo of Loeb by his bed.

Leopold and Loeb became infamous, inspiring fictional works like “Rope” and “Compulsion.” Selzer writes about other notorious murderers, too, including Harm Drenth, whose reign of terror reached the screen as “The Night of the Hunter.” And serial killer H.H. Holmes, whose elaborate “Murder Castle” inspired the bestseller “The Devil in the White City.”

In between gruesome autopsy photographs, Selzer features glamorous victims, too. Like the vivacious Thelma Todd, a 1930s actress whose bloodied body was found slumped in her car. Or the actor and director William Desmond Taylor.

Son of a New York society family, Taylor was busy in Hollywood until he was found dead in his L.A. apartment. A doctor stated that he died of a stomach hemorrhage “which seemed suspicious” considering he was shot in the back.

Neither crime was ever solved.

The saddest stories here are of victims whose names we don’t know, lives that are only known for the way they ended. Some are still awaiting for justice. As “Murder Maps USA” shows, often the clues remain.

All that’s missing is someone to put them together.