JOHN KRUTH clearly intends to revere his subject’s memory in TO LIVE’S TO FLY: THE BALLAD OF THE LATE, GREAT TOWNES VAN ZANDT, a biography of the difficult, beautiful mess that was Van Zandt before his 1997 death at age 52. But while Kruth admirably focuses on the singer-songwriter’s music—he’s best known for writing “Pancho and Lefty,” a hit for Willie Nelson and Merle Haggard—he also acknowledges his legendary bouts of drunkenness and drug use (though, curiously, he lets Van Zandt’s junk addiction go unmentioned for the first third of the book, until the offhand disclosure that the musician was “trying to kick his heroin habit”). Kruth relies heavily on interviews with friends, family, and colleagues, who might be overly fawning in their praise of the lanky troubadour’s charisma and genius but are equally brutal confronting his personal failings and crippling depression. Van Zandt’s legacy is complicated, and he’s survived by an uneven body of recorded work and an ongoing estate battle over royalties. This flawed biography is only a start at making sense of it all.