A criminal prosecution isn’t a fast process. Instead, it is better looked as long investigation in which the state begins with reasonable suspicion and grows to convincing a jury to a near certainty—beyond a reasonable doubt. But each of these investigations must start on the “ground floor.” This takes place not with the prosecutor, but with the police.

The Occurrence
A criminal prosecution begins with the violation of a statute. Kansas has statutes that touch nearly every aspect of its citizens’ lives. Statutes tell you how fast you can drive and forbid you for taking property from other people. But not all “bad” acts are illegal; instead, statutes are composed of a series of acts, called “elements,” and a crime is only committed if each element occurs.

For example, imagine a teen, age 16, asks his older brother, age 21, to buy him some beer to consume. Section 21-5607, makes it a crime for anyone to buy or distribute any alcoholic liquor to a minor. Imagine the brother agrees to buy the beer, but then reconsiders. There, the crime has not been committed. Brother cannot be punished for only considering the illegal actions. Now imagine brother agrees, takes money from the teen, and drives to the nearest liquor store. Again, still not enough for a violation of Section 21-5607. Instead, the brother has to actual buy the beer to complete the crime. Not until the last element has occurred is that specific crime committed. Most crimes may be charged as incomplete crimes (such as attempted theft) or planned but not executed crimes (conspiracy to commit theft). However, even in these cases, the charged violation will be for the attempt or conspiracy, not for the full crime. Only when all the elements are met can the state successfully prosecute an individual for that crime.

Police Involvement
Once a crime has occurred, the first step is information getting to the police. This can occur quickly and completely when an officer sees the full crime unfold. Imagine the teen rode along with his brother to the store and waited in the car. When the brother came out, he handed a beer to the teen and the teen drank from the can. If a police officer watched this entire interaction, he may well approach the vehicle and arrest the brother. Viewing the crime, gave the officer probable cause to believe the brother committed the crime, and that is enough justification to allow the officer to arrest the brother—even without a warrant. The officer also doesn’t need to see the complete crime transpire. So long as the officer sees enough to form probable cause that he has witnessed a crime being committed, the individual can be arrested and taken to holding pending the decision to charge.

Police do not always get a front row seat for crimes. Instead, other individuals may observe criminal activity or what they think is criminal activity. These individuals can report what they see to local police departments, either using emergency lines (such as 911) or non-emergency means (generally making a report at the station). When the information is coming from a non-officer “an informant” the officer is not permitted to take the drastic step of jumping to arrest. Instead, an investigation is generally opened, where an officer attempts to gather enough information to form probable cause that a crime has occurred. This process can include taking statements from witnesses or individuals that claim to have knowledge of the crime, visiting alleged crime scenes, and perhaps even following suspects. These investigation steps can all be completed without a search warrant, because they are considered outside the definition of a Fourth Amendment “search.”

Gathering Evidence
There are significant limits on what tactics officers can use in investigating criminal activity. The Fourth Amendment ensures that police officers do not place investigations of alleged crimes ahead of an individual’s right to have a private life free from the state’s interference. For example, an officer may stop by a suspect’s house or job to ask questions. However, the owner of the property—the suspect or the employer—can demand the officer leave and refuse to answer any questions. Additionally, if the suspect was not home, the officer would not be able to enter the home or apartment to look around for any evidence. Instead, the officer must seek a warrant to search anywhere that a person has a “reasonable expectation of privacy.”

Don’t be fooled, though: “reasonable expectation of privacy” is more of a legal term of art than an accurate description of where an officer can’t search. An officer can “tail” a suspect by following that suspect around from place to place. A normal person would find this annoying and unreasonable, but the officer is free to go anywhere open to the public in investigating. This includes parking on the street outside a suspect’s home, even for days at a time. In California vs. Greenwood, the Supreme Court even found that when an individual places garbage on the curb to be taken away, an officer can open these bags and go through them freely. Again, these investigation techniques are highly objectionable to most people, but courts have found them to be acceptable methods of searching without a warrant.

It is also important to remember that the protections of the Bill of Rights belong to each individual. This means that an individual can decline to use these rights. Police will often approach the accused individual wanting to ask questions. An individual has no obligation to answer any questions, but officers have no obligation to tell the suspect this fact. Additionally, if an officer stops by the accused’s home and is invited in, any evidence of criminal acts left out in the open may be collected by the officer.

Getting A Search Warrant
Officers have one final, very powerful investigation tool: a search warrant. An officer can present evidence to a judge that demonstrate probable cause to believe a certain piece of evidence is located at a certain place. The judge can then sign a search warrant, allowing the officer to search the property over the objections of the owner and despite the owner having a reasonable expectation of privacy. Any evidence found in these searches can be used in the investigation of the crime. Once enough of this evidence is obtained, the officer will hand the matter over to the prosecutor to seek an arrest warrant for the suspect.