After she left her homeland alone as a teenager, Sabina Khorramdel found life as an artist in New York City. And now she had earned a residency abroad — if she could raise the money.

“You have an amazing gift and soon all the world will see,” a man, Thomas Gannon, who owned a Pennsylvania tile company, wrote on a website where she was raising money for the trip. He gave her a $1,000 gift, her largest, adding, “I love you❤️”

On Oct. 28, a housekeeper found Ms. Khorramdel, 33, dead in a nearly $1,500-a-night guest room in a luxuriously austere spa-resort in the Hamptons, according to the Suffolk County police. The police said she had been murdered, but provided no details about the killing or the motive.

By Wednesday, Mr. Gannon was also dead. The police, who described him as the suspect in her murder, said he had shot himself in his home in Honesdale, Pa., in the Poconos.

Mr. Gannon, 56, had been Ms. Khorramdel’s boyfriend and benefactor, according to Elizabeth Phillips, her mentor and former art professor at the State University of New York at Purchase.

“She was naïve about the consequences of this type of relationship,” Ms. Phillips said. “Nobody imagines anything like this, but I did say be careful.”