12. Ricardo, a third-year law student, was subjected to custodial investigation for the crime of Rape. He was duly informed by the police of his right to remain silent and his right to have counsel of his choice if he could afford one, and if not, he could be provided with one. Ricardo proudly informed the arresting officer that he is perfectly aware of his rights, being a law student, and that he is voluntarily waiving them. He then proceeded to issue a written statement truthfully detailing his participation in the crime of Rape. During trial, his written statement was presented as the primary evidence of his guilt. Atty. Alexander, counsel for Ricardo, promptly and vociferously objected to the presentation and admissibility of his written statement on the ground that Ricardo executed it without assistance of counsel. Is the objection justified and tenable? Explain briefly.