Who decides to charge someone with a crime?DA? police?

Charging decisions are made by the law enforcement agency
investigating the crime or the District Attorney (DA). For relatively minor offenses or
misdemeanors the police decide whether or not to file charges, (charge someone with a
crime). It is then the DA's decision to prosecute or
not.

In more complicated cases or those which have been
under investigation, the police agency consults with the DA's office and investigator's
and a charging decision is made based upon the exsisting evidence (if any). At this
point, the case may continue (decision was made to try and prosecute the crime), or the
case may be dropped. The most common reason cases are dropped is insufficient
evidence.

Still, in other cases, the government (DA) takes
the case to the Grand Jury and presents the evidence. The Grand Jury is a group of
laypeople that have been called into service. In this scenario, the DA makes a decision
to charge or not based on the input received from the GJ.