Relevancy of statements: signed responses to summons may be admitted when the declarant is unavailable or court permits in justice. Section 136 renders a statement made and signed in response to a summons under section 70 relevant in prosecutions to prove its truth when the declarant is unavailable for evidence (dead, cannot be found, incapable, kept away by an adverse party, or presence would cause unreasonable delay or expense), or when the declarant is examined and the court, considering the circumstances, admits the statement in the interest of justice.