Last year's American Idol winner, David Cook, isn't often seen without the initial "AC" on his guitar. They were there in honor of his brother Adam, who battled with brain cancer.
Sadly, Adam passed away this weekend from his illness.
Warning. This video is going to make you cry.
David was set to speak at the Race for Hope in Washington, DC, after running in the charity race that benefits the National Brain Tumor Society and Accelerate Brain Cancer Cure.
In the pouring rain and after raising a lot of money for the cause, Cook bravely shared the information that his brother passed with the crowd.
Adam Cook, 37, leaves behind a wife and children.
So very sad.