An expert witness's opinion on the future dangerousness of a defendant is proper evidence at the punishment phase. Jurors may consider what sentence will punish the defendant and what sentence is appropriate to deter future criminal conduct of a defendant. Lopez v. State, 860 S.W.2d 938, 946 (Tex. App. - San Antonio 1993, no pet.). An expert may testify at the punishment stage of trial about a particular defendant's propensity to commit violence in the future. Wunneburger v. State, 844 S.W.2d 864, 869 (Tex. App. - Amarillo 1992, pet. ref'd). However, an expert witness may not recommend a particular punishment to the jury. Id. If a defendant cannot be rehabilitated, the jury may extend his sentence to protect society. Lopez, 860 S.W.2d at 946. Rule 702, governing testimony by experts, requires that such testimony be helpful to the jury. TEX. R. EVID. 702; Perkins v. State, 902 S.W.2d 88, 93 (Tex. App. - El Paso 1995, pet. ref'd). The trial court must determine whether the proffered expert testimony is sufficiently reliable and relevant to help the jury in reaching accurate results. Jordan v. State, 928 S.W.2d 550, 555 (Tex. Cr. App. 1996). Evidence may be offered by the state and the defendant as to any matter the court deems relevant to sentencing, including but not limited to the prior criminal record of the defendant, his general reputation, his character, and opinion regarding his character, the circumstances of the offense for which he is being tried, and . . . any other evidence of an extraneous crime or bad act . . . .TEX. CODE CRIM. PROC. ANN. art. 37.07, 3(a) (Vernon Supp. 2000). Relevant evidence is that evidence that has a tendency to make a fact of consequence more or less probable than it would be without the evidence. TEX. R. EVID. 401. However, there are no facts of consequence at the punishment phase of a criminal trial. Miller-El v. State, 782 S.W.2d 892, 895 (Tex. Cr. App. 1990). Evidence is relevant to the assessment of punishment if it provides information about the defendant's life and characteristics. Brooks v. State, 961 S.W.2d 396, 396-400 (Tex. App. - Houston [1st Dist.] 1997, no pet.). The Legislature has declared that the issue of sudden passion is relevant to punishment. At the punishment phase of a murder trial, the defendant may prove that he caused the death under the immediate influence of sudden passion arising from an adequate cause. TEX. PEN. CODE ANN. 19.02(d) (Vernon 1994). If the defendant obtains an affirmative finding on sudden passion, the offense is punishable as a second degree felony, instead of a felony of the first degree. Id.