Issuing a denial on a supposed crime, or felony, does not necessarily mean that the person is actually denying his/her implication in a crime, or being guilty of it, but it can come from the person´s knowledge that unless there is an open admittance of guilt, an open confession without duress, a person will not be found guilty until the parts prove otherwise. What does give a suspect added confidence, more than a denial, is the knowledge that he/she is considered innocent until proven guilty.
I believe the answer is false. There are many more factors that go into determining whether a suspect is guilty or innocent during an interrogation. Spoken denials may not convince the interrogator.
The police largely exists for the enforcement of civil law and secondly for solving crime cases. The police are known as law enforcement agents. That also carry out detailed investigations into crime cases as they attempt to solve crime of various sorts.