It is well established that, in certain circumstances, a party may present the prior testimony of a declarant who is unavailable to testify under Connecticut Code of Evidence §8-6(1). Following a jury trial, Julio Morquecho was convicted of murder in connection with the fatal stabbing of Maria Chulca, the mother of his children. Morquecho appealed claiming, first, that the trial court improperly admitted expert testimony on domestic violence. The Appellate Court affirmed the judgment. The expert did not testify with regard to any specific facts of this case and did not opine that the victim was a victim of domestic abuse. He defined the term "domestic violence," discussed different types of domestic violence, and testified with regard to traits exhibited by victims generally. The defendant argued that the court should have excluded the testimony because it was unlikely to have assisted the jury which could have resolved the issues from its common knowledge and every day experience. The defendant failed to demonstrate that the expert's testimony would not assist the jury in understanding the evidence, specifically, the nature of the victim's behavior in relation to the defendant, which was relevant to evaluating whether he caused her death. There was ample evidence that the victim feared the defendant and attempted to end her contact with him. To the extent that this evidence might have appeared to contradict a finding that the victim interacted with the defendant, even briefly, at the time of the murder, the expert's testimony concerning the conduct of domestic violence victims was useful to appraise the victim's conduct and determine whether the defendant was the perpetrator. The trial court did not improperly permit the state to present the prior testimony of the victim's boyfriend, Abel Quinde, from the probable cause hearing after finding him unavailable. Quinde's mother testified that Quinde was living in Ecuador and did not want to return to Connecticut, for fear of the defendant. Others, including a detective, testified to contacting Quinde and unsuccessfully trying to convince him to return. Given the ample evidence of the state's timely and significant efforts to secure Quinde's live testimony, the trial court's determination that the state made reasonable efforts was not an abuse of discretion.