(a) By Reputation or Opinion.
(1) In General. When evidence of a person’s character or character trait is admissible, it may be proved by testimony about the person’s reputation or by testimony in the form of an opinion. On cross-examination of the character witness, inquiry may be made into relevant specific instances of the person’s conduct.
(2) Accused’s Character in a Criminal Case. In the guilt stage of a criminal case, a witness may testify to the defendant’s character or character trait only if, before the day of the offense, the witness was familiar with the defendant’s reputation or the facts or information that form the basis of the witness’s opinion.
(b) By Specific Instances of Conduct. When a person’s character or character trait is an essential element of a charge, claim, or defense, the character or trait may also be proved by relevant specific instances of the person’s conduct.