Proximity Between Arrest and Confession Is a Factor to Determine Voluntariness
In Brown v. Illinois, 422 U.S. 590, 45 L. Ed. 2d 416, 95 S. Ct. 2254 (1975), the Supreme Court held that it was constitutional error to adopt a per se rule that Miranda warnings in and of themselves broke the causal chain between the primary illegality and the defendant's confession and held that the statement must be sufficiently "an act of free will unaffected by the initial illegality." Brown, 422 U.S. at 603, 45 L. Ed. 2d at 427, 95 S. Ct. at 2261.
While the Miranda warnings are an important factor in determining exploitation of illegality, they are not the only factor.
Other factors to consider are the temporal proximity of the arrest and the confession, the presence of intervening circumstances and the purpose and flagrancy of the official misconduct. Brown, 422 U.S. at 603-04, 45 L. Ed. 2d at 427, 95 S. Ct. at 2261-62.