Once you've been arrested, the police can search you. Even if in actual fact, you have not committed a crime, if the police reasonably suspect that you are committing one, they are allowed to stop you and frisk for weapons. This means they pat-down your clothing and are allowed to withdraw any object that feels like a weapon. The Miranda warning does not apply to the frisk search. The police may assign the criminal report to a detective.
Detectives are police officers that specialize in investigating crime.
They will normally return to the scene of the crime to review or gather more evidence. They may requisition laboratory tests on objects found at the scene of the crime such as DNA tests. The police report goes to the prosecutor's office. The public prosecutor makes the decision whether to file formal criminal charges or not, usually based on the prosecutor's impression on the strength of the police's evidence. The suspect makes an initial appearance before a judge and pleads guilty or not guilty.