If a felony crime (non-violent) that specifies perpetrator must have wilful intent has been reported and police receive substantial evidence from victim who knows the perpetrator and knows the law and specifies exactly how the law was broken and provides evidence surrounding intent (that is that the suspect, when confronted, lied and blamed someone else who then proved with absolute documentation they did not do it but facts prove perpetrator who lied did), can the police simply drop the issue and say there is 'nothing to charge' based solely upon police personal interpretation of suspect's intent without ever even asking the suspect a single thing? Or getting the suspect's side of the story at all?

Conversely, in an entirely different crime, if a crime is suspected and wilful intent is required to prove there was a crime can the police bring charges, even arrest a suspect without ever having asked the suspect for their side of the story at all?

In other words, must a police investigation of 'intent' include questioning both sides of the alleged crime? Or is that just left up to the court to decide? And if that is the case, must both crimes have charges brought

It's called prosecutorial dscretion. The state, through the police or the prosecutor, is not required to prosecute anyone.

Yes, sir, I understand that. My question is about making that determination to prosecute or not. Are the police obligated to look at both sides to come to a conclusion about intent? (in crimes requiring a wilful intent). Thanks.

I don't know where you are. In NY the Police only investigate until they believe they have enough info to arrest. They don't play Judge and jury.

The. Police investigate.

The DA ultimately approves or disapproves any charges regardless of the wishes of the PD.

In order for the DA to approve a case , they have to believe that they have even a chance of winning it. They have evidence and information that you are not aware of. A factual accusation can be negated by a half factual defense.

The burden if proof for the government is beyond a reasonable doubt. If a defense lawyer can raise a reasonable doubt even in the mind if one out if 12 jurors... the defense wins. Trials cost money and not every case is worth pursuing.