I had assumed a bestselling crime fiction writer who is also an experienced physician and former anthropology student at Stanford University would be pretty thorough when it came to plotting her stories.
I was wrong.
"It's certainly not a case of scrupulous planning on my part," says Tess Gerritsen, author of the mega-bestselling Rizzoli & Isles series, which also enjoys a huge following in its television incarnation.
"I usually start a story with an intriguing situation in mind and the first draft is all about figuring out how it ends," she says.
In Gerritsen's latest crime thriller Last to Die, Boston detective Jane Rizzoli and medical examiner Maura Isles are faced with one of the most baffling cases they've encountered. Three separate family massacres leave three children orphaned. Years later their foster families are despatched in similarly suspicious circumstances.
Now these children, formerly strangers to each other, are brought together as students at Evensong, a remote, heavily protected boarding school in the Maine wilderness. At last the children feel safe. But not for long . . .
"I imagined three children, in different cities, who survive family massacres," says Gerritsen of Last to Die. "Now it's two years later, and these same three children are once again attacked - and survive. What ties these three children together? I had no idea what the solution was and I figured it out as I went."
Gerritsen, who lives with her husband in Maine, says the main inspiration for Last to Die stems from a childhood fantasy to be like fictional sleuth Nancy Drew.
"That's a fantasy shared by many children: that they can prove themselves as clever and capable as an adult, that even an ordinary and powerless child can be a hero."
Thus in Evensong Gerritsen created "a whole school of potential heroes who are ready and willing to be sleuths".
Gerritsen's climb to the top of the fictional sleuthing ladder also has its roots in childhood. "I'm drawn to crime fiction because of a childhood spent watching a few too many horror films," she says.
Consequently Gerritsen has always felt that the height of entertainment is to frighten her audience. "And the fact that I'm a physician means I can do it in an anatomically correct way."
Last to Die is published by Bantam Press ($29.95).