Emergency Interrogation Room Special

A mysterious case has been brought up to the Tokyo Metropolitan Police Department’s Emergency Response Team or Kintori, as they receive a request to interrogate a suspect who had turned herself in for another murder hours after having been released from prison. With forensic evidence that the crime must have taken place at least a week ago, it would have been impossible for her to execute the crime even though the body and murder weapon with are in line with her statement. What is the reason for the lie, and how can the Kintori prove it?