The 33-year-old shot himself in the head at this Las Vegas home, reported Rolling Stone magazine.
The Clark County coroner's office confirmed Marth was pronounced dead of a gunshot wound to the head on Monday. He was found in the backyard.
Marth played on live tours with the 'Read My Mind' hitmakers between 2008 and 2010 and performed on their albums 'Sam's Town' and 'Day & Age'.
A tweet from the band's official Twitter account earlier this week announced Marth's passing, saying the band's prayers are with his family and that "there's a light missing in Las Vegas tonight."