R&B singer and "American Idol" winner Ruben Studdard is mourning the death of his big brother, Kevin Studdard. The cause of death has not been revealed. Ruben Studdard said in an Instagram post, "I thank God for giving me the Best Big Brother ever!!! He has always had my back and looked out for me . He always told me what i needed to hear even when i didn’t want to listen. I love you my kind sweet brother and i will miss you everyday. #RIH I Love you so much @studslife."