Does imposing solitary confinement on a prisoner while police and prosecutors investigate and consider new criminal charges amount to an 'arrest' giving rise to speedy trial protections?

QUESTION PRESENTED In United States v. Gouveia, this Court left open the question whether transferring a prisoner to solitary confinement for purposes of “detention” while police and prosecutors investigate and consider new criminal charges amounts to an arrest that activates speedy trial rights. 467 U.S. 180, 189-90 & n.6 (1984). Since that time, this Court has recognized that prolonged solitary confinement often constitutes an “atypical and significant” additional restriction on liberty because it deprives prisoners of “almost any environmental or sensory stimuli and of almost all human contact.” Wilkinson v. Austin, 545 U.S. 209, 214, 224 (2005). The question presented is: Does imposing solitary confinement on a prisoner while police and prosecutors investigate and consider new criminal charges amount to an “arrest” giving rise to speedy trial protections?