In Ryan v. State, 988 P.2d 46 (Wyo. 1999), the Court addressed the propriety of allowing an expert to testify, under the scope of the battered woman syndrome, as to the characteristics of batterers and the type of conduct they tend to exhibit. In particular, the expert explained to the jury the concept of "separation violence," in which an escalation of violence occurs because perpetrators of domestic violence feel a loss of power and control over their partners when the partners are planning to leave or have left the relationship. 988 P.2d at 53. In Ryan, the expert then testified about the common characteristics of batterers. Id. The court recognized the expert did not specifically state that, because the defendant was violent, he acted in conformity therewith on the night of the murder; rather, the expert subtly and impliedly invited the jury to group the defendant among other batterers to determine his conduct. 988 P.2d at 55. Although battered-woman-syndrome testimony is admissible and helpful to the jury, it must not run afoul of W.R.E. 404(a) which provides in pertinent part: "Evidence of a person's character or a trait of his character is not admissible for the purpose of proving that he acted in conformity therewith on a particular occasion." When battered-woman-syndrome testimony is raised by the state in its case-in-chief and relates to a defendant, as it did in the instant case, the "testimony 'draws close to commenting directly on what likely happened' and 'looks like character evidence after all.'" Ryan, 988 P.2d at 55. Evidence concerning a defendant's involvement demands close scrutiny under the character evidence rules. Id. "This is so even if reference to the defendant may only be inferred from the testimony." Id. The expert in the instant case testified as to the general characteristics and conduct of batterers, with particular focus on the tendency for violence to escalate over time. The Court discussed this concept in Ryan and stated: Finding guilt by reference to common characteristics of a class of individuals to which one belongs raises the specter of profile evidence. Profile or syndrome evidence is developed through expert testimony and tends to classify people by their shared physical, emotional, or mental characteristics. Translated into the battering spouse context, a profile is a compilation of characteristics repeatedly seen in those who batter their spouses. Id. The Court continued: While our research has not disclosed any case dealing specifically with battering spouses, other jurisdictions in different contexts have dealt with similar attempts to construct a criminal profile for the purpose of proving conduct in conformity therewith. Those jurisdictions that have considered profiles of battering parents, pedophiles, rapists, and drug couriers unanimously agree that the prosecution may not offer such evidence in its case-in-chief as substantive evidence of guilt. These cases generally articulate three evidentiary bases for excluding evidence tending to establish that the defendant fits a particular profile: relevancy; probative value substantially outweighed by prejudicial effect; impermissible character evidence. Id. The Court recognized that, although profile evidence may be relevant, the danger of unfair prejudice has generally been found to outweigh the probative value, and the profile evidence is often an impermissible attack on the defendant's character. 988 P.2d at 56. Therefore, in Ryan the Court held the expert's testimony regarding separation violence was inadmissible because it was introduced for the purpose of proving the defendant committed the act in contrast to his assertion that the victim committed suicide. Id.