“She was a very determined young woman; she was charming and so enthusiastic,” said Linda Amiel Burns, founder of The Singing Experience. “This is just unbelievable what happened to her. I’m stunned.”

In the culmination of the workshop, where participants perform for each other, Ms. Ausheva appeared in a red cocktail dress and sang “ Over the Spanish Sky ,” mostly in Russian.

At the end of the song, she gave a short speech. “One year ago I moved from Russia, that’s when my first dream came true,” she said, still not completely fluent in English. “Then in summer I joined U.S. Army — that’s when my second dream came true. Now I’m singing on the stage, on real stage not a shower. You know, my third dream came true and now I wonder what’s next.”

The following year, Ms. Ausheva enrolled in the workshop again and took on a new challenge in her final performance: singing in English.

“When I first met her she was hesitant about her English, but then she came back and said, ‘I want to sing “Santa Baby,” I want to be American,’” Ms. Burns said. “It was so courageous for her to do that and she was so proud to be American.”

In November 2014, Ms. Ausheva transferred to the Air National Guard, according to a military spokeswoman. She was serving full time on active duty with the homeland security force based at Fort Hamilton.

The father of her children, Mr. Walker, also served in the Army National Guard and later joined the Air National Guard, officials said. He was working as a vehicle operator. The authorities said they were unsure whether Ms. Ausheva and Mr. Walker were married.