What prompted his descent from being that darling of writers’ conventions to increasing reclusion in his third-floor apartment? Which of the terrible facts he shared of his background were true, and did they, ultimately, explain everything else?

“It was the bizarro death of a man who lived a bizarro life,” said Andrew Porter, a Brooklyn writer who was among the first to announce Mr. MacIntyre’s demise, on the sci-fi fan blog File 770. “What was his real name? Where was he born? No one knows. Froggy was weird, and his death is just as weird.”

HIS writing was prolific and varied. There was the well-received “The Woman Between the Worlds” (Dell Trade Paperback, 1994), an early example of the genre now called steampunk, and “MacIntyre’s Improbable Bestiary” (Wildside Press, 2001), a collection of light verse praised by Isaac Asimov. Asimov’s Science Fiction magazine published Mr. MacIntyre’s short stories, including “Martian Walkabout” (1980), as did the magazines Amazing Stories and Weird Tales. Mr. MacIntyre ghost-wrote books, too, including the Tom Swift novel “The DNA Disaster” (Pocket Books/Archway, 1991).

He was a huge, gentle fellow with red hair, beard and bushy sideburns, who played the role of a Victorian adventurer-raconteur, dressing in tweed suits, riding boots, white gloves and a Scottish Highlands leather pouch known as a sporran. Writer friends knew him as a worldly bon vivant with an acerbic wit. He corresponded with many literary types and would share photographs of himself posing with them at Oxford and other impressive settings during European adventures.

“Froggy always presented himself as like an English clubman, an eccentric who might be a time traveler from the 19th century,” Mr. Schweitzer, his friend and agent, said. “He was always meeting someone famous in some remote part of the world  Mother Teresa, Idi Amin  and you couldn’t confirm or deny any of it.”

Take, for instance, his gloves, which he said he wore to hide his hands. “He claimed he had a hideous skin condition, but there was also the webbed-fingers story,” Mr. Schweitzer said, noting that Mr. MacIntyre had told some people that webbed fingers were the origin of his nickname, and others that it derived from an obscene phrase his father called him. “Other times, he’d claim he had prosthetics,” Mr. Schweitzer noted, “and then there was the story about having had his fingernails pulled out by Idi Amin’s soldiers while working as a reporter in Africa.”