During a custodial interrogation, the defendant’s statement, “I don’t want to say nothing. I don’t know,” was an ambiguous statement such that a reasonable police officer in the circumstances would not have understood him to be invoking his right to remain silent because the defendant’s addition of “I don’t know” created ambiguity as to whether he sought to invoke his right to remain silent, and, therefore, the circuit court properly denied the defendant’s motion to suppress his subsequent statements for failure to give the proper Miranda