Celebrity Biographer Wendy Leigh Dead in Possible Suicide

Author Wendy Leigh – who penned the best-selling biographies of David Bowie, Patrick Swayze, Arnold Schwarzenegger and others – died on Sunday. The New York Post reports that she jumped from her balcony in an apparent suicide, while it has also been reported that she fell. She was 65 years old.

Leigh's agent Daniel Strone confirmed her death to PEOPLE.

"She was an eternally optimistic and upbeat person," Strone said. "She always was up for an adventure."

Strone also said Leigh loved to work. "Every project she threw her whole body and soul into. She could not wait for the next project," he said. "There was no deadline she couldn't meet. She never lost her cool and never lost her temper."

The late author was said to be distraught over the December death of her 88-year-old mother, Marion.

"Five months today since my mother Marion died. I wish I could say it gets easier, but the truth is quite the reverse…" Leigh wrote in a May 22 Facebook post.

"She really was struggling with that," Strone says. "She was so upbeat and optimistic though, you never really understood what she was going through. She obviously was going through something much more traumatic than she let on."

Two weeks ago, Leigh put her "sexy, stylish" London flat up for sale, advertising its Chelsea Bridge and River Thames views. Strone said she lived in the same building as her mother.

Leigh also recently tweeted the link to an article about depression, quoting "I woke crying, and I went to sleep crying. It still didn't occur to me that I was depressed."

"She has a lot of friends around the world and in London," Strone said. "They were all trying to be her good friend when she needed it."

In addition to her celebrity biographies, Leigh also ghostwrote Christopher Ciccone's Life with my Sister Madonna, freelanced for the Daily Mail, and penned the popular eroticia series, Unraveled. The series, about a celebrity ghostwriter who falls in love with an older man, was assumed to be about Leigh's relationship with British media proprietor Robert Maxwell, who helped her break into the business.