I'm not a reader of cozy mysteries, at least not since I finished all of Agatha Christie's works, but my wife and I do enjoy watching the cozies on the Hallmark Mystery Channel. In spite the entertainment value they afford, they make me wonder what is it in the backgrounds of these amateur detectives that draws them to sleuthing and makes them good at it? As fictional characters, do they need a specific skill background to make them believable, or is their motivation enough?
A case in point. I loved the TV show “Murder, She Wrote,” and still watch it in reruns whenever I can. But, in my opinion, the show had one major flaw; it never explained what made J.B. Fletcher a great crime solver. Upon becoming a widow, J. B., a retired school teacher, takes up writing mysteries and is suddenly capable of solving crimes better than professional investigators. The show hinted that J.B.'s in-depth research for her books gave her the edge.
I find that reason hard to believe. For my military mystery thriller, The Killing Depths, I did extensive research on submarines and their tactics. I read books. I talked to submariners. I toured a Los Angeles-class submarine. None of that, however, made me a submariner.
In real life, of course, not all detectives are great investigators. All detectives pretty much get the same training. In the field, many simply follow well-established routines without adding any special insight. Those who bring something special to the investigation become legends. The same is true in fiction.
For instance, in the TV show “Monk,” the character played by Tony Shalube, is a trained detective, just as his former captain is. But what makes Monk a superlative sleuth is his attention to the smallest detail, a quirk spawned by his out-of-control obsessive compulsive disorder (OCD). In one episode, Monk is given medication for his condition. The drug cures the OCD, but also robs Monk of his deductive powers.
The successes of Arthur Conan Doyle's Sherlock Holmes were also due to the consulting detective's compulsive attention to detail generated by his obsessively restless mind. When not solving an impossible case, Holmes kept his mind busy with crime-related research (like identifying the differences in the ash left behind by different brands of tobacco). When his restless mind wasn't engaged in such endeavors, he resorted to a seven percent solution of cocaine to calm it.
In his Billy Boyle WWII mystery series, author James R. Benn faced similar background problem as I saw in “Murder, She Wrote.” Billy is a young, inexperienced Boston policeman who gets drafted only days after receiving his gold detective badge—which he got largely due to family influence. The Army assigns Billy to Gen. Dwight Eisenhower's staff as a special investigator, not knowing his investigative experience is virtually nonexistent.
Benn, however, cleverly avoided "the J.B. Fletcher problem." Billy's father was a successful Boston police detective who mentored his son's police career, always making sure Billy was on scene for any murder investigation so he could learn the trade. When a case stumps Billy in his role as Ike's investigator, he falls back on the lessons he learned from his father's mentoring.
In David Morrell's inaugural thriller, First Blood—the book that gave us Rambo—the author had a young Vietnam vet fighting off repeated assaults by police officers and National Guard soldiers. Contrary to what many people think, most service members are not highly trained in combat skills. For every trigger puller on the front line, there are 10 soldiers sitting behind computer consoles and desks, driving trucks, and pumping gas. Only because Morrell made Rambo a veteran of the Army Special Forces was it believable he could struggle against the overwhelming forces thrown against him by the book's antagonist, a sheriff in the rural South.
Morrell said he based Rambo on Audie Murphy, America's most decorated hero of WWII. But what was it about Murphy—a short, skinny Texas teenager rejected by the paratroops and the Marines—that made him such an effective combat soldier? After all, he received the same training as other infantry soldiers.
The answer lies in Murphy's childhood. Coming from a fatherless, Depression Era family, Murphy took on the responsibility of the man of the house at an early age. He provided for his mother and siblings by hunting for food and working odd jobs for money, instilling in the boy a strong sense of obligation to take care of others. In combat, his skills with a rifle and his sense of responsibility for his fellow GIs made this baby-faced soldier a superb combat leader.
In his Reacher series, author Lee Child's hero is a former Army military police major who roams the country taking on odd jobs and righting wrongs, sometimes with extreme prejudice. As a former state guard major of military police myself, I can't see me doing anything like that. However, Child built a detailed background for Reacher to explain his actions. (He's not just a MP, but led a special Army criminal investigative unit; he's an expert in martial arts, etc.)
On the other hand, Alfred Hitchcock gave us several examples where an "Everyman" character is thrown into mystery and danger, and comes out triumphant in the end. North by Northwest and The 39 Steps (based on a novel by John Buchan) come readily to mind.
So does your character need to have a specific background to become a success crime solver, or is motivation enough? A topic for more debate, I think.