Although Magdalen Nabb was not as well known as two other writers of crime novels set in Italy, Michael Dibdin (obituary, April 5 ) and Donna Leon, her Florence-based mysteries were as subtle and accurate as any contemporary portrait of the country.

The protagonist of her 13 stories, from Death of an Englishman (1981) to The Innocent (2005), was the overweight, clumsy, patient and astute Marshal Salvatore Guarnaccia. Like Nabb, he is an outsider, a Sicilian, and like her, too, was unusually sensitive to moods and nuances of behaviour and speech.

Around him Nabb depicted a city that was less the tourist postcard than a melancholy sprawl plagued by Italy’s current preoccupations – among them Albanian prostitutes and kidnap gangs – and by its history. Several of her books drew on famous cases investigated by the carabinieri, such as the serial killer nicknamed the “Monster of Florence”, and she had excellent contacts in the police, even venturing into the hills of Sardinia to interview criminals.

Her reliance on psychological rather than physical action, her pared-down vocabulary and her depiction of Guarnaccia’s home life inevitably drew comparison’s with Georges Simenon’s Inspector Maigret, and indeed Simenon was godfather to her work. He wrote to Nabb praising her first book, and thereafter encouraged her and introduced her to her literary agent, the Swiss publisher Diogenes.

In time, her books were to be translated into more than a dozen languages, although only recently had she become popular in Italian itself.

She was born Magdalen Nuttall in the Lancashire village of Church, near Blackburn. She was one of three sisters, and her parents died when she was still young, but not before she had inherited the artistic leanings of both. She was educated at Bury Convent Grammar School, and after art college in Manchester trained as a teacher and taught at a primary school in Holcombe Brook, near Bury.

By the mid1970s she had had a son, but her marriage to James Nabb had come to an end and, after holidaying in Florence, she decided to move there – despite not speaking the language. The art, religion – she was a Roman Catholic – and love of life all spoke to her, and allowed her to remake herself. She was always grateful for that and, unlike many expatriates, never complained about Italy’s perceived shortcomings.

At first she worked as a potter at Montelupo, outside Florence, where at a restaurant she encountered the policemen who would become the models for those in her books. One of them had an allergy to sunlight, a characteristic she would give to Guarnaccia. Later she and her son lived in the pensione where E. M. Forster had written A Room with a View, and for several years in the late 1970s and early 1980s she was the curator of Casa Guidi, Browning’s house.

It was there that she set her first novel, Death of an Englishman, originally intended as something of a pastiche of Agatha Christie. Later novels in the series included Death of a Dutchman (1982), The Marshal and the Murderer (1987) and Property of Blood (1999).

Although she undertook much research for the books, she never plotted a synopsis of the work in hand, being content to wait until it emerged of its own accord, although she sometimes felt compelled to sleep near her computer to supervise and encourage its birth. She had recently completed a new Guarnaccia mystery, Vita Nuova, which will be published next year.

From 1989 she began a series of books for children about Josie Smith. Again, this was a portrait of her own childhood, fatherless and short of money, and the stories were even set in the same village of Ramsbottom, Lancashire. The second of them, Josie and Eileen (1991), won the Smarties Book Prize for six to eight-year-olds, and the books were later adapted for television by Granada.

Her other work included The Enchanted Horse (2001), the royalties from which she gave to the Brooke Hospital for Animals. She much enjoyed riding, and undertook several equine-related projects for the charity in Africa and Afghanistan.

Magda Nabb was a strong-minded woman, whose force of character was such that her petite frame often surprised those who met her for the first time. She was brave and without self-pity, and after being paralysed down her left side by a stroke a dozen years ago had refused, when many might have done otherwise, to give up riding or ballet. She had an unusually wide circle of friends that embraced academics and shopkeepers, many of whom she entertained to memorable dinners at her apartment looking out on to the trees of the Boboli Gardens.

She died after suffering a stroke while out riding. Her son survives her.

Magdalen Nabb, author, was born on January 16, 1947. She died on August 18, 2007, aged 60