Over the last century or so, science has utterly changed the way crimes are investigated and solved. It has even, in some cases, redefined what constitutes a crime.Two new nonfiction books delve into the fascinating history of those changes. In The Art of Forgery, American art historian and novelist Noah Charney looks at not just how art forgeries are committed and solved, but why forgers are driven to commit such crimes. In Forensics, bestselling Scottish crime novelist Val McDermid digs into the details of methods used to read crime scenes and corpses in real life — methods that also serve as rich material for so many mystery writers.From forgery to fraudAs Charney points out in The Art of Forgery, copying a painting or other work of art is not a crime. Indeed, it's one of the basic methods by which artists learn: "Renaissance apprentices learned by copying the works of their master, with the goal of making their work indistinguishable from his. It was only after a pupil produced his 'masterpiece' and became a master himself that it became possible to develop his own distinctive style."One of the greatest artists of the Renaissance, he writes, got his start as a forger: As a young man, Michelangelo made a marble sculpture that he passed off as an ancient Roman work, because such pieces were considered much more valuable than newly created ones. When the forgery was discovered, it only helped Michelangelo's career, because it demonstrated his skills.In more recent times, however, attitudes about faked artworks have changed. A crime occurs not when a copy is made but when it's passed off as the work of another artist and sold — the crime is not forgery but fraud. Charney explains some of the many amazing ways in which such frauds are committed, but what he's most interested in is why they happen. Thus, he organizes his book according to the motives he perceives in the cases of notable forgers: pride, revenge, fame, power and more.Money, he writes, is often not a major motivation but is secondary to others, such as the artists he writes about in the "Revenge" chapter whose own original works failed, but whose skills were good enough that they could make and sell convincing fakes.Charney also reveals the reverberations forgeries can cause, well beyond a duped buyer. Auction houses and dealers that, knowingly or not, sell fakes and museums that add them to their collections may lose credibility; phony works may influence scholars' evaluations of an artist's genuine creations.Historically, the authentication of art fell to connoisseurs, people whose combination of learning and intuition was considered the gold standard. The last few decades brought to art fraud investigation the same forensic tools used to solve other crimes, such as analysis of materials. Investigators also now have improved ways to verify a work's provenance — the records of its creation and ownership. Tampa Bay area readers will find several sections of local interest in The Art of Forgery. In his chapter on "Fame," Charney writes about successful art forger Ken Perenyi, a longtime resident of Madeira Beach, who in 2012 published Caveat Emptor (Latin for "buyer beware"), a colorful memoir recounting his long career in fraud. In the "Pride" chapter, Charney covers Salvador Dalí, whose works, especially his lithographs, have been widely faked: "Around 12,000 fake Dalí prints were seized in a single investigation. Dalí is the second most frequently forged artist (behind only Picasso) and is known to have signed blank canvases to be filled in later by other artists." Novelist Stan Lauryssens, who for a time was a dealer in fake Dalí prints, claimed in his 2008 memoir that the surrealist artist may have authenticated forgeries of his work in exchange for a share of the profits.Matches and maggotsIn Forensics, McDermid, the author of 29 mystery novels, makes no bones about the importance of her subject matter to her own work: "(T)he truth is that crime fiction proper only began with an evidence-based legal system. And that is what those pioneering scientists and detectives bequeathed us."Thanks to crime fiction and its on-screen offshoots, we've become accustomed to the idea of scientific methods being used in investigations. But, McDermid points out, that's a relatively recent development. When Sir Arthur Conan Doyle wrote in the 1880s about Sherlock Holmes' monograph on identifying different kinds of cigar ashes, it was an outlandish touch because no such research then existed. Reading Doyle's stories, though, served as an inspiration to Edmond Locard, who actually did similar research decades later and, in 1910, opened the world's first crime investigation laboratory in Lyons, France.Locard is just one of the pioneers of forensics that McDermid sketches, focusing mostly on cases and scientists in the United Kingdom. She also notes differences in crime investigation between the United States and the U.K., which has a centralized system that makes it "possible to get a DNA profile in just nine hours on a straightforward bloodstain," something that in this country happens only on TV.Forensics is organized by method, with chapters on fire scene investigation, toxicology, blood spatter, facial reconstruction and more. Every chapter is packed with facts that are by turns astonishing — matches don't burn away in arson fires because their heads are covered in ground fossilized diatoms, single-cell algae whose 8,000 different species can be identified and used to track a match to its source — and disturbing, like the study that showed that 80 percent of sleeping children were not awakened by fire alarms.And then there's the just plain revolting, including pretty much the entire chapter on entomology (the study of insects). As gleefully as a kid, McDermid recounts how scientists have learned to pinpoint (using such technology as miniature CT scanners) the exact developmental stage of blowfly maggots commonly found in dumped corpses and use that to determine how long a victim has been dead. It's fascinating, but don't read it over dinner.McDermid points out that new methods have increased the demands on those who work in the forensic field to capture every detail. She quotes pathologist Dick Shepherd on doing autopsies: "I have to say my heart sinks now when it's a pub fight and there's 970 2 cm bruises. Can't I just say there were lots of bruises on the legs? No."It has also created a somewhat false picture of what forensics can do among the public, known as "the CSI effect." Not only do tests take longer than they do in an hourlong TV episode, but they're not always relevant or reliable. Even DNA testing, McDermid writes, is fallible despite its enormous impact. And sometimes the fascination with forensics goes too far. "Forensics scientist Val Tomlinson says, 'It can be your Senior Investigating Officer who's not had a lot of time on the ground. I remember going to one scene where a man was sitting dead with a knife in him and the SIO said, "Oh, so you will be doing metal analysis on the edges of the cut so that you can show it was that knife?" And I said, 'Maybe that's not our priority given the knife is sticking out of him.' "Contact Colette Bancroft at [email protected]ay.com or (727) 893-8435. Follow @colettemb.