Martha Stewart’s younger sister Laura Plimpton died unexpectedly on Monday after suffering a brain aneurysm. She was 59.

Martha Stewart's Sister Dies

Stewart, 73, announced her sister’s sudden death in an email to her lifestyle company, according to the Daily Mail. Plimpton had long worked at Stewart’s side at the company and held a senior position there.

“My youngest sister, and the youngest of the six Kostyra siblings, Laura Kostyra Plimpton, passed away today in Norwalk Hospital. Laura worked for me and the company for more than 25 years,” Stewart wrote in the email, according to the British tabloid.

“She was an extraordinary employee, mother, wife and sister,” Stewart said, adding that Plimpton’s organs had been donating in her passing. “We are so sad but also happy that Laura had the foresight to donate so many healthy organs to needy people.”

Apparently, Plimpton had been working out at her home Monday morning when she began to feel unwell. She and her husband Randy phoned for help and she was subsequently rushed to the hospital. Plimpton, a mother of three children, was found to have suffered a brain aneurysm.

Stewart and Plimpton have been close since childhood, despite their considerable age difference. When Stewart was embattled by legal trouble, her sister defended her on Larry King, where she also demonstrated how much she’d always looked up to her.

"All I wanted to do was be around her, her husband, and then when Alexis was born, I just wanted to take care of Alexis," she told Larry King. "I would pack my little suitcase and go every weekend, practically, just to be with Martha."