We review a district court's findings of fact on a motion to suppress an admission or a confession to determine whether the findings are clearly erroneous. A finding of fact is clearly erroneous if it is not supported by substantial evidence, if the district court misapprehended the effect of the evidence, or if this Court has a definite or firm conviction that the district court committed a mistake. State v. Loh, 275 Mont. 460, 475, 914 P.2d 592, 601 (1996).
Substantial evidence requires more than a mere scintilla of evidence, but may be less than a preponderance of the evidence. State v. Scarborough, 2000 MT 301, ¶ 30, 302 Mont. 350, 14 P.3d 1202.
The voluntariness of a confession or admission is a factual question which must take into account the totality of the circumstances. State v. Loh, 275 Mont. 460, 475, 914 P.2d 592, 601 (1996).
The issue of voluntariness is largely a factual question committed to the district court's discretion. We will not reverse that court if its order is supported by substantial credible evidence. State v. Beach, 217 Mont. 132, 151, 705 P.2d 94 (1985).
Where determination of voluntariness depends upon the credibility of witnesses, this Court must defer to the district court judge who is in a superior position to judge the credibility of those witnesses. State v. Scarborough, 2000 MT 301, ¶ 30, 302 Mont. 350, 14 P.3d 1202.
The burden of proof of voluntariness is upon the State, and it is required to prove voluntariness by a preponderance of the evidence but not beyond a reasonable doubt. State v. Grimestad, 183 Mont. 29, 36, 598 P.2d 198, 202 (1979).