What would Dionnis Coffin Riggs do?

That’s the question Cynthia Riggs asks herself every time she finds Victoria Trumbull, the protagonist in her mystery book series, in a precarious situation.

“She is patterned as closely as I could make her after my mother, and yet she has taken on a life of her own,” Ms. Riggs said at her family home the Cleaveland House in West Tisbury this week. “Victoria is her own self.”

The 92-year-old Victoria Trumbull appears once again as the lead detective in Ms. Riggs’s latest novel, Poison Ivy. She takes on a new role this time as adjunct professor of poetry at Ivy Green, a small college on the Vineyard. But when the issue of tenure arises among faculty members, dead bodies start appearing.

“I’ve always been interested in academic politics and I have four academicians in my family,” Ms. Riggs said. “I asked to them, could you give me some horror tales? And they just flooded me with stories.”

“I figured I had to have a serial killer,” she added.

Ms. Riggs wrote the novel in 2010, during which a biology professor at the University of Alabama murdered three faculty members who had been denied tenure. Tenure, she decided, was a perfect motive for murder.

New murderers but similar themes of Island gossip and familiar characters are hallmarks of Ms. Riggs’s writing, including Victoria Trumbull’s trusty canine companion Brownie and the West Tisbury police chief Mary Kathleen O’Neill. One avid reader noticed the absence of the “greek chorus” on the front porch of Alley’s General Store in Ms. Riggs’s last novel, The Bee Balm Murders. Ms. Riggs received an email from the reader, Bruce Steinbicker, who said he missed the porch sitters.

“You didn’t have them in the last book and I think you should put them back in,” Ms. Riggs recalled the email saying.

In response Ms. Riggs wrote in a cameo appearance by a handsome young television star named Bruce Steinbicker who arrives at Alley’s. Then she went one step further.

“His character took over,” she said. “He ends up having an affair with a married woman . . . and it occurred to me the real Bruce Steinbicker might not be comfortable with this. I wrote to him and said . . . if this is causing you any problems in your personal life I’d be happy to change the name. He wrote back and said, ‘I showed this to my wife of 55 years and she just laughed.’”

The mystery series was formerly published by St. Martin’s Press, but after a buyout of the company, Ms. Riggs thought it would be more beneficial to self-publish her work. Her publishing house is called Cleaveland House Books and Poison Ivy is the first book under her new imprint.

“I felt comfortable publishing, I knew how to do it,” Ms. Riggs said because she had previously published her mother’s and father’s books. She’s also writing and publishing a new book due out in September, which is part of another mystery series based on the waterfront in Washington, D.C.

“I used to live on a boat there and it was just a wonderful life,” she said. “Nobody thinks of D.C. in terms of boating life.”

Murder on Sea Dock will be “a lot darker” than the Trumbull novels, she warned.

In addition to starting her own publishing company and working on her novels, Ms. Riggs has had quite a year, finding a long-lost love at the age of 81 and marrying him over Memorial Day Weekend. But her betrothed, Howard Attebery, won’t have an effect on the characters, at least not consciously.

Dr. Attebery is a retired dentist and their relationship was rekindled while she was writing her next book in the series, Bloodroot, due out next April. “It’s about a murder in a dental office,” she laughed. “And here’s Howie with a dental degree. Isn’t that weird?”

Ms. Riggs still diligently sits at her writer’s desk in her office on a daily basis as she has done for her past 10 novels, though her time management priorities have changed.

“Before I got into this relationship, I didn’t realize how much time relationships took,” Ms. Riggs said. “Before that I was very disciplined . . . I could easily write a chapter a day.”

Now Ms. Riggs happily splits her time between her garden, her books and her husband.