Life Bluegrass musician Jeff Austin, co-founder of Yonder Mountain String Band, dies at 45 June 26, 2019 Hannah Yasharoff, USA TODAY Comments Off on Bluegrass musician Jeff Austin, co-founder of Yonder Mountain String Band, dies at 45 Bluegrass musician Jeff Austin, who co-founded the Yonder Mountain String Band, died Monday at 45 after cancelling shows for a "medical emergency."