In 1994, members of the doomsday cult Order of the Solar Temple began to die in mass murders and suicides. Across Switzerland, France and Canada, bodies were found charred, shot in the head, poisoned, and more.

In three years, more than 70 people linked to the cult died, including children. One, a three-month-old baby, had been stabbed to death with a wooden stake.

Some of those bodies went to the Quebec laboratory where forensic anthropologist Kathy Reichs worked. Although she did not work on them herself - she specialises in bodies that are less fresh - she observed their autopsies.

Years later, the memory of those cult victims would inspire her to write psychological thriller Two Nights, her first standalone novel in years.

"When I started this book, I thought of that again," says the 69-year-old American crime writer. "What would it be like for a person growing up in that situation, where everyone they knew or loved had died?"

Reichs is most famous for penning the Temperance Brennan series, which combines her decades of forensics experience with the gritty thrill of the crime novel.

She has published 18 novels in the best-selling series since 1997, which inspired Fox television show Bones (2005-2017), a crime procedural starring Emily Deschanel as forensic anthropologist Temperance Brennan.

Given the long-running success of the Temperance formula, she was reluctant at first to strike out anew.

Her publisher convinced her otherwise. Speaking over the telephone from London, where she is on a book tour, she says: "It turned out to be great fun not to have to stay consistent with all the facts I had spent 18 books creating."

Her new hard-boiled heroine, the implausibly named Sunday Night, is a far cry from the level-headed, cerebral Temperance.

Sunday, a scarred, gun-toting former cop, is persuaded out of her reclusive existence to help find a missing teenager. The girl is thought to have been kidnapped by the cult that killed her mother and brother in the bombing of a Jewish girls' school - something which resonates with Sunday's own dark childhood.

While the mass murders and suicides of members of cults such as Solar Temple, Heaven's Gate and Peoples Temple may seem a thing of the past, Reichs sees parallels to the recruiting of young people by terrorist organisations today.

Citing the case of a 16-year-old German girl who joined the Islamic State of Iraq and Syria and was arrested in Mosul last month, she says: "How do they recruit these kids to kill people and kill themselves?"

Reichs has a storied forensics career - she has testified before a United Nations criminal tribunal for the Rwandan genocide, helped exhume a mass grave in Guatemala and identified remains at Ground Zero of the 9/11 bombings.

She also served as a producer on Bones, which came to an end in March this year after 12 seasons. It was an emotional farewell for her, but she says: "You want to go out while you're on top."

She is proud of having kept Bones as scientifically accurate as possible, instead of it being "one of those shows where they get the DNA results in 20 minutes".

Although the show has depicted numerous bodies in various states of decay, her favourite remains the first, the pilot episode's "lady in the lake". She has pictures of herself lying on the ground next to the body.

The mother of three continues to consult on particularly complicated forensics cases, juggling this with her writing career. She is working on a 19th Temperance novel and is not ruling out more adventures for Sunday.

The most important thing about forensics work, she says, is remaining emotionally detached. "Otherwise, you can't do your job."

That is not easy to do, especially when it comes to children.

Her first case involving a child was that of a five-year-old girl whose skeleton was found in a wooded area.

"I'd been working with skeletons for years," she says, "but they were ancient, whereas this was a child who had died months ago."

She puts into her heroines her own passion to "get a name so these victims don't go into an anonymous grave or sit on the medical examiner's shelf - and in the case of homicides, to get justice, get the perpetrator off the streets".

While she has always enjoyed crime fiction by the likes of noir master Raymond Chandler and thriller writers Ian Rankin, Harlan Coben and Dennis Lehane, she is glad to see more female representation in the genre in the last few years.

"A couple of decades ago, we didn't have so many strong heroines. I hope little girls are inspired to become forensic scientists and cops when they grow up."

•Two Nights by Kathy Reichs ($28.95) is available from major bookstores.