"What happens now?..."
When the police are called to a crime an investigation is conducted. The responding officer gathers evidence that may include fingerprints, photographs, diagrams and statements. Once the evidence is gathered, the officer evaluates the evidence to determine whether or not it is appropriate to proceed with an arrest.
In many cases an arrest is made while the officer is on scene. In other cases the officer may choose to seek an arrest warrant for the suspect and return at a later date to make an arrest. In both cases there are many things that occur before the case makes its way into the courtroom.
The first step in the process is with the investigating officer(s) and that is the police report. The report details the facts of the offense and describes how the evidence shows the suspect is responsible for the commission of the alleged crime.
The next step is a review of that report by the officer's supervisor. If the supervisor concurs with the officer the report is approved and sent to the Detective Division for further investigation and warrant request, if required.
The Detective Sergeant conducts a second review of the report before forwarding the report to the district attorney. In the review process, the supervisors may ask the officer to conduct additional investigation, gather additional evidence or make corrections to the report. Most reports do not require additional work but in those cases, the report is repaired or the additional work is completed and then forwarded to the district attorney.
The police officer has the burden of determining whether or not "probable cause" exists to make an arrest. IT simply means that a reasonable person would conclude the accused committed the alleged crime and should be brought before the court. The district attorney has the burden of making to determination whether or not the accused is guilty beyond a reasonable doubt. Occasionally the police will make an arrest but the district attorney concludes there is not enough evidence to meet the higher burden, proof beyond and reasonable doubt, so the case is not formally charged. In those cases the law enforcement agency has an opportunity to conduct additional investigation and gathers more evidence. If successful the case can be re-submitted to the district attorney.
Once the case is charged by the district attorney and formal "complaint" is filed and the accused, now a defendant, is brought before the court. The first proceeding before the court is called arraignment. The complaint is read to the defendant, bail is set and the next hearing is set.
Sometime after the arraignment victims and witnesses may be called to testify in a hearing or trial. Subpoenas will be issued by the district attorney's office. A subpoena requires the person served to come before the court on the date and time specified. In all cases a representative from the district attorney's office discusses the case with the witness prior to testimony.