wander from the straight and narrow

Translations
сбиться с пути истинного
Over the years, he began to wander from the straight and narrow and got involved in crime.
С годами он начал сбиваться с пути истинного и увлекаться преступлениями.
Definitions
To stray from a morally correct or socially acceptable path; to engage in behavior that is considered improper or unethical.