A person is an accomplice if there is sufficient evidence connecting him or her to the criminal offense as a blameworthy participant. Blake, 971 S.W.2d at 455. The participation necessary to be considered an accomplice must involve an affirmative act or omission by the witness to promote the commission of the offense. Id. at 454; McFarland, 928 S.W.2d at 514. The test is whether there is sufficient evidence in the record to support a charge against the witness alleged to be an accomplice. Whether the person is actually charged and prosecuted for his or her participation is irrelevant; what matters is the evidence in the record. Blake, 971 S.W.2d at 455. Witnesses may be accomplices as a matter of law. If there exists no doubt or the evidence clearly shows that a witness is an accomplice witness as a matter of law, the trial court is under a duty to so instruct the jury. Blake, 971 S.W.2d at 455. One who is or may be indicted for the same offense with which a defendant is charged, or for a lesser included offense based on alleged participation in the commission of the greater offense, is considered an accomplice as a matter of law. Ex parte Zepeda, 819 S.W.2d 874, 876 (Tex. Crim. App. 1991). If evidence presented by the parties is conflicting, it is proper to leave the question of whether an inculpatory witness is an accomplice witness as a matter of fact to the jury, under instructions defining the term accomplice. Blake, 971 S.W.2d at 455; see Gamez v. State, 737 S.W.2d 315, 322 (Tex. Crim. App. 1987). In Marlo v. State, 720 S.W.2d 496 (Tex. Crim. App. 1986), the Texas Court of Criminal Appeals, in a 5-4 decision, reversed a murder conviction because the trial court failed to submit to the jury the fact issue of whether two key witnesses were accomplices. In that case, the evidence showed that both witnesses were present at the murder scene; that a "common understanding" existed between the appellant and the two witnesses that some offense would be committed; that use of deadly force was contemplated, however jokingly; and that both had participated in the disposal of the body, one of them even washing out the bed of the truck afterward. On the other hand, both witnesses asserted that they never anticipated a murder and that they assisted in the coverup only because they were afraid of the appellant. The majority opinion held that, notwithstanding the fact that these assertions were uncontradicted, they "could very well have been discounted under the circumstances presented in this case," id. at 500, and "whether there existed 'a common understanding, or proof of criminal intent' on the parts of [the witnesses] to commit murder . . . was properly an issue for resolution by the jury, and the trial court erred in not submitting that issue accordingly . . . ." Id. at 501. The dissenting opinion, finding no conflict in the witnesses' testimonies, would not have required submission of the accomplice factual issue to the jury. Marlo, 720 S.W.2d at 503-04 (Onion, J., dissenting). Subsequent cases citing Marlo have emphasized that where there is no conflict in the evidence regarding whether the witness is an accomplice, the trial court may properly refuse to submit that issue to the jury. See, e.g., Herrick v. State, 825 S.W.2d 215, 218 (Tex. App.-Houston [1st Dist.] 1992, no pet.).