Q: What,if any options do I have if the police request a voice and handwriting sample?
A: Give them or face the consequences (maybe an arrest for hindering prosecution or something along those lines). These things are nontestimonial evidence and gathering them is noninvasive; the government is not prohibited by the Constitution or any other law is getting this info from you.
Q: What may the police do if someone refuses to furnish the samples?
A: See answer above.