Your case is regarding the admissibility of a case diary as evidence.
A case diary is a record of daily investigation into a case. Under the provision of Section 172 of the Criminal Procedure Code (CrPC) a police officer conducting the investigation is required to maintain a record of investigation done on each day in a particular case.
The only time the accused person can see the diary is if the court uses the details in the diary to contradict the submissions made by the police officer in the court. This exception is provided by the provisions mentioned under the Indian Evidence Act, 1872.
The supreme court in a recent judgement stated that a criminal court can use the case diary to help an inquiry or trial but not as evidence. This position is made clear by Section 172(2) of the CrPC. The Supreme Court has ruled that no court should rely on a case diary as evidence and acquit or convict an accused on the basis of that.
I hope this solves your query.