Lou Pearlman, the former manager of NSYNC, the Backstreet Boys, O-Town, and a number of other pop acts, has died at the age of 62.

Pearlman, who was in the midst of serving a 25-year sentence following a 2008 conviction for running a Ponzi scheme, died in prison, and the cause of death has not been disclosed. Though he launched the careers of nearly every successful boy band to leave their mark on the late ’90s and early aughts, Pearlman also had a difficult history with many of his clients, and several sued him for fraud and misrepresentation.

As such, a number of Pearlman’s former clients are delicately paying their respects on Twitter. The conflicted feelings were summed up succinctly by NSYNC’s Chris Kirkpatrick as “mixed emotions.”

Justin Timberlake and Lance Bass offered kind, sad words, and refrained from sugarcoating, as did the Backstreet Boys’ AJ McLean and Ashley Parker Angel of O-Town.