What is the test for denying a plaintiff a speedy trial claim de novo?

We review a district court's denial of a speedy trial claim de novo, although factual determinations underlying the decision are reviewed for clear error. United States v. Mendoza, 530 F.3d 758, 762 (9th Cir.2008). Under Barker v. Wingo, 407 U.S. 514, 530, 92 S.Ct. 2182, 33 L.Ed.2d 101 (1972), we must review four factors in determining whether a defendant has been denied his right to a speedy trial: (1) the length of the delay, (2) the reason for the delay, (3) the defendant's prior assertion of the right, and (4) the prejudice resulting from the delay.