Michael Babich, who resigned as the Arizona-based drugmaker’s CEO in 2015, pleaded guilty in federal court in Boston to conspiracy and mail fraud charges after entering into a cooperation deal with prosecutors.

His plea comes less than three weeks before five former Insys executives and managers including John Kapoor, its onetime billionaire founder and former chairman, face trial after being charged with participating in the scheme.

Babich, 42, faces up to 25 years in prison. But the Arizona resident could receive a more lenient sentence by testifying at Kapoor’s Jan. 28 trial. Assistant U.S. Attorney Fred Wyshak in court said Babich committed his crimes at Kapoor’s direction.