Whether a criminal defendant's confession is voluntary is a mixed question of fact and law and is reviewed de novo Commonwealth v. Shoiter, 2007 MP 20 P 6, 7 N. Mar. I. 488. Due process requirements exist to prevent fundamental unfairness in the use of evidence. Colorado v. Connelly, 479 U.S. 157, 167, 107 S. Ct. 515, 93 L. Ed. 2d 473 (1986) (citing Lisenba v. California, 314 U.S. 219, 236, 62 S. Ct. 280, 86 L. Ed. 166 (1941)). The Fifth Amendment of the United States Constitution ensures that defendants are protected against self-incrimination and the inherently coercive effects of custodial interrogations. U.S. Const, amend. V; see also NMI Const. Art. I 5. a defendant in a criminal case is deprived of due process when a conviction is founded, in whole or in part, upon an involuntary confession. Rogers v. Richmond, 365 U.S. 534, 540-41, 81 S. Ct. 735, 5 L. Ed. 2d 760 (1961). A motion to suppress evidence is used to remove involuntary confessions from consideration, as well as other evidence in a criminal trial that is secured coercively or in an otherwise illegal manner. Commonwealth v. Campbell, 4 N.M.I. 11, 14 n.1 (1993), aff'd, 42 F.3d 546 (9th Cir. 1994). In Miranda v. Arizona, the United States Supreme Court determined that statements stemming from a custodial interrogation are inadmissible unless the defendant is first apprised of his or her constitutional right to silence and assistance of counsel. 384 U.S. 436, 445, 86 S. Ct. 1602, 16 L. Ed. 2d 694 (1966). Defendants are in "custody" when they are formally arrested or otherwise deprived of their freedom of action in any significant way. Id.; see also Orozco v. Texas, 394 U.S. 324, 327, 89 S. Ct. 1095, 22 L. Ed. 2d 311 (1969). Additionally, "'interrogation' under Miranda refers not only to express questioning, but also any words or actions on the part of the police . . . that the police should know are reasonably likely to elicit an incriminating response from the suspect." Commonwealth v. Yan, 4 NMI 334, 338 (1996) (quoting Rhode Island v. Innis, 446 U.S. 291, 301, 100 S. Ct. 1682, 64 L. Ed. 2d 297 (1980)). The Commonwealth has the burden of establishing that a defendant "intelligently, knowingly, and voluntarily waived his or her procedural due process rights." Shoiter, 2007 MP 20 P 8, 7 N. Mar. I. 488. Thus, "where Miranda safeguards apply, the prosecution may not introduce evidence procured without the protection afforded by both proper warnings and a valid waiver of those warnings." Yan, 4 NMI at 334, 338 (citing Commonwealth v. Cabrera, 4 NMI 240, 253 (Atalig, J., dissenting)). In assessing whether a defendant validly waived his or her Miranda rights, "we examine the totality of the circumstances." Commonwealth v. Ramangmau, 4 NMI 227, 235 (1995). Relevant circumstances include "the characteristics of the defendant and the details of questioning by the government." Id. Additionally, we examine whether a defendant endured "physical threats of harm, deprivation of sleep or food, lengthy questioning, and psychological persuasion." Id. at 236. We also examine whether the "police knew that the respondent was unusually disoriented or upset at the time of [the] arrest." Yan, 4 NMI at 338 (quoting Innis, 446 U.S. at 303). Absent coercive police activity, a confession will not be considered involuntary. Cabrera, 4 NMI at 246 (1995).