Because Yamada Yonegoro had a perfect alibi, even though the DNA retrieved matched his, he could not be convicted on this evidence alone.
Such an obvious flaw would be seized upon by any competent attorney in court for a defense of innocence, so the police could not ignore it and forcefully convict Yamada Yonegoro. They had no choice but to interrogate him overtime, hoping to find a new breakthrough.
While the police continued to interrogate Yamada Yonegoro for a breakthrough, Kube Rokuro, at the request of Misumi Mikoto, visited Tokyo University Medical School Hospital to see Chen Yu and confirm matters again.
As the son of Professor Kube and a frequent visitor of Chen Yu, the nurses at the hospital had come to recognize Kube Rokuro, so they greeted him when he arrived.
