Kevin Burns has stepped down as chief executive of embattled e-cigarette maker Juul, amid intensifying scrutiny of the brand's marketing practices and a public health crisis that has seen nine deaths related to vaping products and 530 confirmed cases of vaping-related lung disease.

Burns will be replaced by K.C. Crosthwaite, a former executive at tobacco-maker Altria, which took a 35 percent stake in Juul last year.

Crosthwaite will continue “a broad review of the company’s practices and policies to ensure alignment with its aim of responsible leadership within the industry,” Juul said in a statement released on Wednesday.

Juul also announced it will withdraw all advertising in the U.S. The company had already axed its youth-focused social media marketing after the Food and Drug Administration demanded action from e-cigarette makers due to the huge spike in teen vaping use. Juul also nixed kid-friendly flavors such as mango and fruit.

Officials in Kansas confirmed on Monday the state's second death from the mysterious vaping disease, bringing the total number of fatalities to nine.

Health officials are seeing “more and more cases” every day, the Centers for Disease Control told a congressional panel at an emergency hearing on Tuesday. Patients experience coughing, fever, trouble breathing, chest pain, vomiting, diarrhea and general fatigue. The majority of patients are between the ages of 18 and 34, and nearly three-quarters are men, according to the CDC.

Federal prosecutors in California are reportedly conducting a criminal probe into Juul for deceptive marketing practices that targeted minors, according to the Wall Street Journal.

Philip Morris and Altria announced Wednesday the two companies are no longer considering a $200 billion merger that would have reunited the two companies after they split in 2008 to focus on international and the domestic markets, respectively. The merger had originally been intended to strengthen the companies' bottom line as they face a retrenching in the tobacco industry due to the increasing popularity of vaping products.

Instead, the two companies will now focus on launching IQOS, a heated tobacco product that has already received FDA approval — unlike Juul.