Colin Cotterill was born October 2, 1952, in London and grew up near Wimbledon, where he was an avid reader of comic books, material that inspired his own love of illustration. He attended Berkshire College, earning a teacher-training diploma in 1975, and afterward embarked on a career as a teacher, teaching instructor, and curriculum developer that led him to various parts of the world. He was a physical education instructor in Israel before moving to Australia, where from he taught grades four through six at Corpus Christi in Glenroy, Victoria. In Perth, Western Australia, Cotterill worked with refugees from Vietnam, Cambodia, Laos, and Burma as a teacher with the Migrant Education Department (1978-1979), an experience that spurred his further interest in Southeast Asia. After receiving a graduate diploma at Sydney University, Cotterill worked in New South Wales as an adult migrant educator (1980-1982) and as a materials developer (1985-1986). Between stints, he taught (1982-1983) at Tokai University, Kanagawa, Japan.
From 1986 to 1988, Cotterill served as teacher and curriculum developer at Chiang Mai University in Thailand. For the next two years, working in the television department of Open University in Nonthaburi, Thailand, he was writer, producer, editor, and actor in a nationally broadcast, English-language teaching program in the form of a situation comedy series, English by Accident.
Between 1990 and 1994, under the auspices of the United Nations Educational, Scientific, and Cultural Organization, Cotterill served as a teacher trainer and curriculum developer for the Ministry of Education at Dong Dok University and Dakse Teachers’ College in Vientiane, People’s Democratic Republic of Laos. He returned to Thailand, where from 1995 to 1997 he wrote curricula at Prince of Songkla University in Phuket and became project director for Child-Watch, an organization formed for the protection of sexually abused and exploited children. Cotterill served as a teacher-trainer and materials developer at refugee camps on the Thai-Burmese border, then received a certificate in community welfare from the Sydney Institute of Technology in Australia.
After serving another year with Child-Watch—during which time Cotterill wrote articles and drew cartoons for local publications, and produced a novel and two nonfictional books about child protection, published in English in Thailand—he became involved with ECPAT International (End Child Prostitution, Child Pornography and Trafficking of Children for Sexual Purposes). For two years he acted as training coordinator for the organization in Bangkok.
In 2002, Cotterill settled in northern Thailand, where he works as a writer, cartoonist, and occasional graduate teacher at Chiang Mai University. Following the publication of another Thai-published novel, Evil in the Land Without: From England to Burma, a Monster Seeks Revenge (2003), Cotterill released his first internationally distributed novel, The Coroner’s Lunch, which introduced the mystery series character Dr. Siri Paiboun. The series continued with Thirty-three Teeth, which won the Dilys Award; Disco for the Departed (2006); and Anarchy and Old Dogs (2007). He contributed a Dr. Siri short story to Damn Near Dead: An Anthology of Geezer Noir (2006) and also published a comic novel, Pool and Its Role in Asian Communism (2005), available only in Thailand. Cotterill was married in 2006.