A friend of mine received his permanent resident status in 90's. In 1999 while living in Texas, he made a mistake for hitting his wife and was arrested. The charge was class A misdemeanor. After completion of a family violence course, evaluation by a psychiatrist, and a marriage counseling course, his case was dismissed.
He has clean record before and stay clean after the incident. He is an ordinary law complying person, except that one incident. Now he is planning to apply for citizenship, but was advised that he may lose his PR status and could be deported. Is that always true? How risky is it if he does apply for citizenship?
Thanks in advance for any advice.

