How Do Criminal Investigations Work?

Amatrix Investigations is a private investigation firm in Los Angeles. Our team has a solid track record of playing very active and pivotal roles in criminal defense investigations. While law enforcement at the municipal, state, and even federal levels have substantial resources for investigating criminal activity, private investigation firms like Amatrix Investigations provide critical support. Our additional investigative resources can aid a wrongfully accused or overcharged individual facing conviction.

We work with criminal defense attorneys and Pro Per clients throughout Southern California to bring greater balance to California’s criminal justice system. Police and other law enforcement agencies pursue criminal convictions quite aggressively. Unfortunately, the drive to secure swift convictions often leads to innocent people facing charges they do not deserve. We believe it’s vital for everyone to understand how criminal investigations work and the role that private investigation firms like Amatrix Investigations play in the process.

What are the steps in a criminal investigation?

Law enforcement and government agents have much more freedom when it comes to the pre-arrest investigation. They have the right to cordon off crime scenes and gather physical evidence, whereas private investigators do not. Private investigators cannot trespass on private property or enter a crime scene the police control. They cannot arrest or intimidate suspects, and they cannot access many of the digital resources that the police and government agents typically use in their investigations. However, the fundamental investigative techniques employed by Amatrix Investigations have proven invaluable in countless cases helping the wrongfully accused avoid unjust punishment. Private investigators often play crucial roles in the pre-trial investigation phase, but their participation in criminal investigations also extends further into most cases.

It is also important to remember that a private investigation firm like Amatrix Investigations can help an individual facing a wrongful accusation of a crime. Unfortunately, some law enforcement officials are so aggressive in pursuing convictions they refuse to consider (and sometimes even hide) exculpatory evidence so they can save time and resources on their investigation efforts while inflating their conviction record.

Once the police make an arrest in a criminal investigation, the suspect is booked and must make an initial appearance. The court will read the charges against the suspect and advise them of their constitutional right to counsel and their right to remain silent. At this point, the prosecution process begins. However, this does not necessarily mean the investigation is over. If a suspect hires a criminal defense attorney, their legal team may coordinate with a private investigation firm to locate any evidence that could lead to reduced or dropped charges for their client.

What Are the Three Methods of Investigation?

The criminal investigation process of virtually any crime is complex and multifaceted. While many crimes lead to open-and-shut cases, these incidents require clear evidence of a suspect’s guilt and readily available corroborating evidence that proves the suspect’s guilt beyond a reasonable doubt. It is not uncommon for some criminal investigations to extend well beyond the investigators’ initial impressions of the case. Law enforcement must fully employ every investigative technique at their disposal. While private investigators do not have the same level of authority or the same resources as law enforcement officials, they must also fully leverage the investigative techniques at their disposal possible.

The police and private investigators typically rely on three main methods of investigating criminal activity:

Evidence Gathering

Evidence gathering is one of the most crucial forms of investigation. This can involve physical examination of the crime scene, the body of the victim, and other material evidence involved in the matter. Depending on the type of crime in question, evidence gathering may also involve deep fact-finding and research to uncover documentation material to the case. Typically, private investigators do not have physical access to most crime scenes. However, this does not mean they cannot use their investigative skills to carefully review crime scene reports and photographs, sometimes identifying evidence that the police overlooked.

One of the most important aspects of evidence gathering is determining admissibility. There are strict laws in place that aim to preserve due process and ensure that all investigative authorities follow the letter of the law as they conduct their investigative work. There have been many occasions in which official investigators have planted or obfuscated evidence to streamline their conviction processes, which often leads to severe criminal penalties for those involved in due process violations. Private investigators must also follow the law, and typically they rely on evidence gathering through careful review of evidence already gathered by police.

Witness Interviews

Interviewing witnesses is another key component of any criminal investigation. This may involve interviewing the complaining witness and direct witnesses to the event in question as well as bystanders who saw some or all of the crime occur. The police will take statements from witnesses they identify during pre-arrest investigation and may need to double back and confirm witnesses’ stories as their investigation unfolds. Private investigators can also conduct witness interviews on behalf of the criminal defense firms who hire them and may even identify other witnesses. For example, a local business owner near a crime scene may have CCTV footage that the police failed to obtain, and this footage could be a deciding factor in the criminal case that unfolds.

While the police have broader authority when it comes to locating and interviewing witnesses, private investigators can also uncover solid evidence through their own interviews. Again, private investigators are not above the law and are private citizens, but they have the experience and resources to sometimes uncover evidence and witness testimony that police and government agents may have overlooked.


Surveillance is another of the most important tools of criminal investigation. Police and law enforcement agencies at all levels may conduct “stakeouts” and surveil points of interest related to a criminal investigation to help them locate and identify suspects and evidence. Private investigators can also use these tools and typically do so in a more flexible manner than the police. Experienced private investigators like the team at Amatrix Investigations are accustomed to blending in with crowds and surveilling persons or places of interest with minimal exposure.

Surveillance can be one of the most critical aspects of an investigation, especially one pertaining to fraud. For example, if an individual is suspected of committing disability or workers’ compensation fraud, a private investigator can help gather evidence that proves their criminal activity.

These three methods are crucial in any criminal investigation. Depending on the nature of the crime, a private investigation firm like Amatrix Investigations will use some or all of these methods to assist in their efforts. It’s important to remember that a private investigator is relatively limited in their investigative methods compared to the police.

Amatrix Investigations leverages years of professional investigative experience and state-of-the-art resources to conduct highly detailed and comprehensive criminal investigations. While private investigators may lack some of the tools and the authority of law enforcement officials, their investigative efforts often prove pivotal in highly complex criminal investigations.

Benefits of Working With a Private Investigator

Private investigators must follow the letter of the law while conducting their investigative activities. Criminal defense firms throughout the country typically form lasting professional relationships with private investigators to help them protect and defend their clients. Private investigators often provide the evidence these attorneys need to help their clients avoid unjust charges, especially when law enforcement is driven to secure a conviction as soon as possible regardless of any evidence indicating they have the wrong suspect.

If you are accused of a crime, it is imperative to secure legal representation from a criminal defense attorney as soon as possible. If you believe that the police are refusing to consider exculpatory evidence, a private investigator could be the lifeline you and your legal team need to prove your innocence. If you happen to become a victim of any type of crime, working with a private investigator can effectively supplement the police’s investigation. If you have specific questions about how a private investigator can help in your unique case, contact Amatrix Investigations today for more information about our services.

© 2023 by Amatrix, Investigations. INC. All rights reserved. Privacy Policy | Site Map
Translate »