“We are incredibly saddened by the news of his passing,” the Estée Lauder Companies’ statement said. “As the visionary behind Deciem, he positively impacted millions of people around the world with his creativity, brilliance and innovation. This is a profound loss for us all.”

News of Mr. Truaxe’s death came after a year of unusual behavior from the Deciem founder, much of which was displayed on social media. In Instagram posts on the company’s account, Mr. Truaxe canceled the company’s marketing plans and canceled company partnerships.

Executives began to leave the company in response to Mr. Truaxe’s odd behavior, including Stephen Kaplan, the company’s chief financial officer, and Nicola Kilner, his co-chief executive, who said her employment was terminated by Mr. Truaxe. (She rejoined the company in the summer.) Mr. Kaplan later explained that he had departed “because Brandon’s demeanor had changed following a December vacation in Mongolia.”

Then, after a relatively quiet period, Mr. Truaxe announced in October that Deciem would shut down its operations, claiming, as an aside, that virtually all of the company’s employees had been involved in “major criminal activity.”

The investors interceded, asking a judge to remove Mr. Truaxe from the company to stop him from hurting the business. “He has essentially lit the company on fire,” a lawyer representing the brand said at the time. The company’s application to oust Mr. Truaxe was granted, and management of Deciem was ceded to Ms. Kilner.