The most recent unsolved murder on Martha’s Vineyard occurred in 1940, when police found 72-year-old widow Clara Smith beaten and strangled to death on her bed in East Chop. Since then, there have been accidental deaths, stabbings, and even the occasional homicide to ruffle the Island’s feathers. But nothing close to a mystery.

Of course, fans of Cynthia Riggs, the octogenarian proprietress of West Tisbury’s Cleveland House Inn, would say otherwise. For them, there have been 13 murder mysteries on the Island in the past 15 years alone. They have ranged from narcissistic newspaper editors to obnoxious motorcyclists to denuded bodies floating in Oak Bluffs Harbor. But unlike Ms. Smith’s 1940 murder, these mysteries aren’t found on mastheads or newsstands. No, they are best enjoyed next to firesides and lamplight. And, thanks to the watchful eye of the perpetually 92-year-old volunteer police deputy and poet, Victoria Trumbull, they always end up solved.

“Agatha Christie is loosely what my books are based on,” said Ms. Riggs, who along with being an innkeeper, sailor, tour guide, and the new owner of two pygmy goats, also happens to write a series of murder mysteries starring sleuth Victoria Trumbull.

“They’re called cozies, which means you can sit in your chair by the fire and read them.”

Widow’s Wreath, Ms. Riggs’ most recent book and the 14th in the Martha’s Vineyard Mystery installment (all have horticultural titles because of Ms. Riggs’ love of gardening), has just hit the shelves, and, like most of its predecessors, is partially autobiographical.

“I had a grandniece who was getting married on the Vineyard,” Ms. Riggs said, “and as a wedding present I told her she could have her reception here.”

Thinking lemonade and cookies, Ms. Riggs was taken aback when two tents, fryers, loudspeakers, and a raw-bar appeared on her property.

“I couldn’t believe this was going on, and I thought, well this is going to be a really great book,” she said.

In Widow’s Wreath, Victoria Trumbull gives her own grandniece the same wedding present, but that’s where the autobiography ends.

“The bride is dead-broke,” Ms. Riggs explained, “but she’s hooked this guy who she thinks is really wealthy. Little does she know, he’s been disowned, and is totally broke too.”

Amid all that intrigue, a dead body appears in Ms. Trumbull’s basement, making for a most mysterious matrimonial weekend.

Victoria Trumbull and Martha’s Vineyard have served as the centerpiece of all 14 of Ms. Riggs’ novels.

“I’d never written anything before my mother died,” Ms. Riggs said. She only started putting the pen to paper when she was 68 and decided to get her MFA from Vermont College. A friend suggested she write murder mysteries because they were the most fun.

“I had no idea what I was doing,” Ms. Riggs said. “I knew I had to have a setting, so Martha’s Vineyard was obvious. And I knew I had to have a character, and my mother was obvious. She died at 99, and I decided to make her much younger at age 92.”

This year, Ms. Riggs turned 87 herself. “I’m sort of realizing now that I’m putting Victoria into situations that are, well, implausible,” she admitted with a smile. “But she’s so closely based on my mother that I feel as if I’m keeping her alive this way.”

Although still nimble enough to tend to her four chickens, four ducks, a rooster, six grown-up guineas, 16 teenage guineas, and two human tenants, Ms. Riggs has recently made use of her electric golf cart just as often as her feet. She even has two new pygmy goats who still need names, a task she’s left to members of the writer’s groups she hosts each week.

“Because they’re two neutered males,” said Ms. Riggs as she fed the goats a seemingly bottomless bale of hay, “one writer suggested I name them Sodom and Gomorrah. I’m in favor.”

The pygmy goats, like the ancient cities, have disproportionately large underbellies.

Yet even as Ms. Riggs focuses more time on her animals, inn and garden, she has no intention of slowing down. “My goal is to write 20 books before I retire. And after that, I want to start learning about horticulture.”

She’s already broke ground on her next novel, A Bittersweet Death (unlike many authors, she starts with a title and goes from there), which has a timely plot-line.

“I figured I’d have a big, undeveloped plot of land that belonged to a family, and it’s kind of a mess. So-and-so wants to keep it. So-and-so wants to sell it.”

Because of a dispute with her most recent publishers (who told Ms. Riggs’ agent that they “were concerned with Cynthia’s pugnacity”) she’s decided to self-publish A Bittersweet Death. Her company, Cleveland House Books, is named after the bed and breakfast she runs.

“I’m only on chapter three,” she said, “but they’ve already found a dead body.”

Like her readers, Ms. Riggs often doesn’t know who the culprit is until the very end of the book. “They call us pantsers,” Ms. Riggs explained, “which means we’re writing by the seat of our pants.”

What she fails to mention is that her readers are pantsers too.