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Bottles containing poison could be found on household shelves a century ago.

If you think the investigators on "C.S.I," "Law and Order" and other cop shows have it tough, imagine what it was like a century ago - when a confessed poisoner went free because no one could prove he did it. Forensic science, as it's practiced today on television and in thousands of real-life crime labs, hadn't yet been invented.

"It wasn't just that they didn't have the tests," Pulitzer-winning science writer Deborah Blum told me today. "They didn't have the apparatus to do the tests."

Blum tells the tale behind the birth of forensic science in "The Poisoner's Handbook," a saga that literally lets readers pick their poison.

The setting for Blum's story is New York City in the early 20th century. This was the era when chief medical examiner Charles Norris and toxicologist Alexander Gettler came up with chemical procedures to tease out the evidence of poisoning from the finely diced tissue of murder victims. It was also the era during which the federal government started adding poisons to alcohol as part of the effort to enforce Prohibition.

Parallel cat-and-mouse games played out during New York's Jazz Age, between bootleggers and anti-alcohol enforcers, and between murderers and medical examiners. Bad hooch surely killed more people than arsenic and cyanide in those days.

"Prohibition chemists didn't have to create exotic formulas," Blum writes. "Wood alcohol, methyl alcohol, whatever you chose to call it, was still the best poison at hand."

Ghastly smorgasbord
Alcohol in its various forms provides the theme for three of the 11 chapters in "The Poisoner's Handbook." Other chapters run through the rest of the ghastly smorgasbord available in the days before and during Prohibition: chloroform and cyanide, alcohol and mercury, thallium and radium.

Back then, many of those poisons were available in pantries and medicine cabinets. There was radium candy (for an energy boost) and radium-laced facial cream (for glowing skin). Arsenic was found in skin treatments and medicines, rat killers and dyes. Chloroform was used in cough syrups and sedatives.

The case that Blum describes in her first chapter focuses on a nursing aide who turned into a serial killer, poisoning his elderly patients with chloroform-soaked rags. Even though the man confessed to the crimes, the coroner erroneously told prosecutors that there was no way to detect chloroform in a corpse. The aide was sent to a mental hospital, but he merely walked out and disappeared before the authorities could catch up with him.

"Their knowledge was so poor that they didn't even realize they could run the tests to prove he did it," Blum said. "They totally could have nailed this guy."

A subtle killer
Carbon monoxide ranked among the subtlest killers, back in the '20s and even today. "It's really one of the most elegant poisons," Blum told me. Almost 500 Americans die each year from accidental carbon monoxide poisoning, mainly due to unventilated heating sources that produce the suffocating gas. Scores of people were poisoned during last month's "Snowmageddon" storm on the East Coast.

Blum explains how each poison does its dirty work and how doctors first learned to detect it. Cyanide molecules, for instance, attach more efficiently to hemoglobin than oxygen can, starving the bloodstream. Its presence could be found by putting a sample of minced tissue from the corpse into a witches' brew of chemicals and watching for the sludge to turn blue.

Those early days are long gone: Today, forensic scientists glean more information from a single shaft of hair or spot of blood than Norris and his pioneering toxicologists could extract from an entire corpse. "If you go into a chemistry lab today, you're not going to see these long tables with Bunsen burners and glass tubing," Blum said. "You're just going to see a lot of machines."

Not a recipe book
On one level, "The Poisoner's Handbook" is a textbook case of chemistry at work. "To me, chemistry is the most beautiful, the most fundamental and in many ways the most sinister of sciences," said Blum, who once dreamed of becoming a chemist.

On another level, the handbook is a guide to chemical hazards that still exist on the fringes of the modern world. "I think people today need to know something about poisons and how they work, so that they can protect themselves," Blum told me.

And on still another level, "The Poisoner's Handbook" is a true crime novel with a chemical kick. The fact that you're learning something can be seen as a mere side effect.

If you're looking to do someone in, don't expect to find the recipe in "The Poisoner's Handbook." (The book might help you figure out how to mix up a Bee's Knees cocktail, which sounds like a pleasant Prohibition poison - but that's about it.)

"No one is going to learn how to poison someone from my book," Blum said. "The Internet's much more dangerous than my book."

The one-time chemistry student, who now brandishes a poison ring on her finger, said she did pick up a lot of laboratory lore during her research. But she purposely kept the how-to information out of "The Poisoner's Handbook."

So does she know how to poison someone if she had to?

"Yeah, I do," she replied. "I hate to say this, but my husband will never have coffee in the same room with me anymore. But having figured those methods out, I'm really planning not to use them. I actually have no interest in killing anyone. I like my husband. I want him to be around for a long time."

Update for 9 p.m. ET: The kinds of poisoning cases we hear about nowadays can be quite sensational: radioactive polonium-210 slipped into a secret agent's tea, for example, or dioxin poisoning that nearly kills a Ukrainian leader. "That's great for a government that's trying to send a message," Blum said. "It doesn't matter that it's a detectable poison that leaves a trail. But most of your homicidal killers, they want to get away with it."

Blum said the most successful poisons are those that don't kill right away, and don't leave much of a trace. "You want a poison that mimics an illness enough that no one does a toxicology screen," she said. Exactly what poison might that be? Blum isn't saying.