If the arrest was unlawful because not based on probable cause, what statements and handwriting samples might be inadmissible as matter illegally seized in violation of the Fourth Amendment?

3 If the arrest were unlawful because not based on probable cause, all statements and handwriting samples taken thereafter might be inadmissible as matter illegally seized in violation of the Fourth Amendment. Cf. Wong Sun v. United States, 371 U.S. 471, 83 S.Ct. 407, 9 L.Ed.2d 441 (1963). We need not reach that question, however, because whether or not the arrest was lawful, all evidence taken once arraignment was unnecessarily delayed was inadmissible under the Mallory rule.