CHUMPORN, Thailand -- Dr. Siri Paiboun was already beyond retirement age when he was appointed state coroner to the morgue in the Lao capital, Vientiane, shortly after Dec. 2, 1975, the day when the land-locked Southeast Asian nation officially became the Lao People's Democratic Republic. Some 12 books later, the famed Lao coroner-cum-detective is still going strong, solving murders, sassing communist officials, messing with the spirit world and slurping down tasty noodles cooked by his second wife, Madame Daeng.

The Dr. Siri detective series, set in the years after Laos fell to communist control in 1975, is the creation of British author Colin Cotterill, 65. After living in Laos, Cotterill settled in Thailand and now lives in the southern town of Chumporn, with seven dogs and his wife, Kyoko, whose family owns a 300-year-old soba noodle restaurant in Shiga, Japan. Like his Dr. Siri alter-ego, Cotterill is also postponing retirement. "The strange thing that happens when you stop writing is the money stops coming in," Cotterill said with typical wry humor.

The author, who is also an accomplished cartoonist, estimates he has sold more than a million copies of the Dr. Siri series, in both print form and e-books. He is working on his 13th Siri mystery, which will be called "Don't Eat Me," about the highly lucrative traffic in animals and animal parts in Laos, Thailand and Vietnam.

Cotterill can boast of being the only Western author of a murder mystery series set in Laos, although the detective genre abounds in neighboring Thailand. Asian-based crime thrillers are popular among expatriate authors in part because they appeal to locally based readers, especially expatriates interested in the countries where the mysteries are set.

"The Dr. Siri series is one of the better-selling ones by expat authors set in Asia, but it doesn't sell quite as well as the John Burdett series about Bangkok," said Don Gilliland, co-owner of the Dasa Book Cafe, a popular second-hand book store in Bangkok. "Christopher Moore [another popular Thai-based author] books also sell well, but almost anything set in Thailand will sell well either to local expats or tourist customers."

Cotterill lives in Chumporn, southern Thailand, with his Japanese wife Kyoko and seven dogs. (Courtesy of Colin Cotterill)

British author Burdett is best known in the region for his thriller novel "Bangkok 8" and other titles in the Sonchai Jitpleecheep series, whose main character is a mixed-race Thai Buddhist police detective. Canadian author Moore, arguably the father of the expat detective genre in Thailand with more than 30 years under his belt in the kingdom, created the Vincent Calvino series, about a Western private eye who solves crimes in various Southeast Asian capitals.

Moore's recent mysteries have taken on a political hue, touching on topics that are sensitive in Thailand, such as military coups, corruption and the judicial immunity of the rich and powerful. "Crime novels are the perfect genre because they are basically about how a system delivers justice or doesn't," said Moore, whose Calvino books have been translated into 12 languages.

Cotterill was a teacher for 27 years before becoming a full-time author. (Photo by Peter Janssen)

Cotterill, who was a teacher for 27 years before becoming a full-time author, chose Laos for his novels, partly because Thailand was already crowded with virtuous crime fighters. "I think the main reason for starting off with Laos was because nobody else was doing it," Cotterill said.

Laos was the theater of the "secret war" for the U.S. military in Indochina, during which an estimated 2 million tons of bombs were dumped on the land-locked country, more than U.S. aircraft dropped on all countries in World War II.

Communist Laos remains secretive. It is the only country in Southeast Asia that has no permanent foreign media presence, partly because so little happens in the country of 7 million. When something does happen, like the mysterious disappearance at a government checkpoint of the country's best-known activist, Sombath Somphone, on Dec. 15, 2012, a cloak of official silence envelopes the case. Sombath's disappearance remains unexplained.

Cotterill has also experienced the enigma of Lao officialdom. After working in the country for several years in the early 1990s, he was suddenly expelled in 1995. He was working in Pakse, southern Laos, on an English-language curriculum for Lao teachers, when he was summoned to Vientiane. "I wasn't expecting to be thrown out of the country, which is what they did. I never did find out why."

Back in Thailand, he became involved in child protection activism in Phuket, southern Thailand, which led to his first series of "serious" novels about child abuse and pornography. They did not sell well.

Nurse Dtui, one of oddball characters in Cotterill's Dr. Siri crime series (Courtesy of Colin Cotterill)

Then he decided to draw on his earlier experiences as a teacher in Laos and among members of the Lao refugee community he knew in Australia. "I remember often sitting in the kitchen of a house in Melbourne with three members of the old Lao Cabinet who were telling me how much damage the socialists were doing to their country," Cotterill recalled.

He embarked on the Dr. Siri series in 2003. "I had the background and the experience, and I'd seen two points of view from two different groups, so for me Laos was a good starting point," Cotterill said.

He settled on the fictitious Dr. Siri Paiboun as his protagonist. Siri was born some time in 1904 and schooled at a temple before getting a scholarship to study medicine in France. Here, he falls in love with his first wife, Bouasawan, an activist who insisted he join the Communist Party to marry her. Siri returns to Laos in 1940 to join the communist guerrillas as a doctor. He survives the war, and is appointed national coroner on his return to Vientiane in 1975, at the ripe old age of 71.

Using a Lao doctor educated in France as his hero provided Cotterill with the "voice" he needed to criticize the communist regime while still sounding sympathetic. "That allowed me to make comments about Laos through the eyes of someone who has studied overseas and lived overseas," he said. "And his humor is probably as English as me."

Some of the most entertaining writing in the Siri series involves the doctor's droll confrontations with Lao bureaucrats and communist officials. The series has won various crime writers' awards, including Dagger in the Library and the Dilys Award, and glowing reviews in the New York Times Book Review and other publications. "The Dr. Siri books are by turns laugh-out-loud funny, sobering, convoluted, historical and endlessly entertaining," according to a BookPage Top Pick post.

Unfortunately, the Siri brand of humor has gone largely unappreciated among Lao people. Although Siri novels have been translated into Danish, Dutch, French, German, Italian, Swedish and Thai, they have never been published in Lao, and a translated version might not pass Lao censors. "Books written in Lao are read at the ministry of culture before being granted an ISBN [international standard book number,]" said Robert Cooper, director of Lao Insight Books, a small publishing house in Vientiane. "There is no censorship and nothing is refused, it just might take forever to get cleared," he added.

Cotterill's Siri series, in English, is available at the departure lounge of Vientiane's Wattay International Airport and can be found at second-hand book stores in the capital. But since most Lao do not read English, the impact is moot. "It is a paradox that Laos is known outside thanks largely to Colin, but Colin is known inside Laos to only a few Lao," said Cooper.

In 2013 and 2014 Cotterill took a break from the Siri series (he usually writes one Siri book a year) to work on a similar crime series based in southern Thailand, in which the protagonist is a female journalist named Jimm Juree. Although sharing the humor and oddball characters that populate the Siri mysteries, the Jimm Juree books did not win the same loyal following among readers. Bowing to popular demand, and financial necessity, Cotterill pulled Dr. Siri out of retirement in 2015 and has been pushing out a Siri story each year since. "It was sad to think that Colin was going to 'retire' Dr. Siri at one point," said Dasa cafe's Gilliland.

Luckily for his fan club, retirement does not seem to be on the cards for Dr. Siri, nor for Cotterill, any time soon. This may be good news for communist Laos as well. "I've had a lot of readers say they went to Laos after reading the series," Cotterill said. "But so far I haven't had a 'thank you' from the Lao Tourism Authority."