Key takeaways
- Understand why correct gang classification forms the foundation of every successful gang case.
- Learn the validated criteria investigators use to confirm membership and withstand courtroom scrutiny.
- Recognize how local context — from tattoos to territory — shapes accurate identification.
- Apply the “totality of circumstances” standard to document membership fairly and defensibly.
- See how misclassifying a suspect can damage credibility, weaken charges and risk dismissal.
The first step in successful gang investigations and prosecutions is identifying the members of a particular gang. It can’t come from hunches — it needs to be based on specific, articulable facts.
It’s important for law enforcement officers to know what allows us to classify someone as a member of an illegal criminal street gang. There will be differences between federal and state legal definitions, and even between states themselves.
One consistent standard at both federal and state levels is that for someone to be identified as a criminal gang member, they must be part of an actual, recognized criminal street gang.
| DOWNLOAD: How to buy evidence management
Recognized criminal street gangs
There are many gangs recognized nationwide — and in some cases, worldwide — that are classified as criminal street gangs. A short list includes:
- Bloods
- Crips
- Norteños (Nuestra Familia)
- Sureños (Mexican Mafia)
- Outlaw motorcycle gangs like the Hells Angels, Mongols and Warlocks
- MS-13 (Mara Salvatrucha)
These gangs have existed for decades. Their members have committed crimes in support of their organizations and have been the subjects of numerous state and federal prosecutions. Each has met the legal definition of an active criminal street gang under applicable statutes.
Proving a new gang is a criminal street gang
Sometimes investigators encounter a gang that has not yet been identified or prosecuted. Proving that a new group qualifies as a criminal street gang presents challenges, but a skilled investigator can overcome them by documenting:
- The gang is a criminal organization whose members commit crimes in support of or for the benefit of the gang.
- The gang has common signs and symbols — such as colors, numbers, clothing or tattoos — that represent affiliation.
- The gang’s members have committed predicate offenses such as drug dealing, shootings, stabbings, murders or human trafficking, establishing a pattern of criminal behavior.
When testifying as a gang expert, investigators must prove the gang’s existence and provide evidence of prior predicate offenses to establish that pattern.
New gangs form frequently. Young members often resist joining older organizations to avoid hierarchy or police attention. Creating new groups allows them to “fly under the radar.” Successfully identifying and prosecuting members of a previously unknown gang is a significant accomplishment — much like an astronomer discovering a new star.
| DOWNLOAD: How to buy interview recording systems
Determining gang membership
Law enforcement takes gang classifications seriously. Investigators only classify individuals as members if there is sufficient corroborating information. The burden of proof is high because prosecutors, defense attorneys, judges and juries will scrutinize gang-related charges closely.
To meet that standard, most investigators rely on established validation criteria that have withstood judicial scrutiny in thousands of cases. Below is an example used by many agencies in California.
Gang member validation criteria
Document any of the criteria below to establish an individual as a gang member.
- Self-admitted: What did the person say?
- Arrested for gang crime (per Penal Code 186.22[e]): List the crime(s).
- Reliable source: Who identified the subject — officer, probation officer, parole agent, etc.?
- Affiliates with gang: List known gang associates.
- Gang hand signs or symbols: Describe what was seen and how it’s gang-related.
- Frequents gang area: Identify the location and explain why it’s considered a “hot spot.”
- Gang dress: Describe the clothing and why it’s gang-related.
- Gang tattoos: Describe and document tattoos.
This isn’t a secret list hidden in a drawer. It’s the same framework gang investigators present in court to support classification.
To validate someone as a gang member, investigators generally need multiple criteria. Classification is based on the totality of the circumstances — several converging factors, not just one. Race or ethnicity is never part of the criteria.
| DOWNLOAD: How to buy investigation software
Applying the criteria: The Abrego Garcia case
Consider the case of Kimber Abrego Garcia, the “Maryland man” deported to El Salvador in connection with his alleged MS-13 membership — a case that still illustrates the importance of solid, defensible classification.
In 2019, officers from the Prince George’s County Police Department (Maryland) made contact with Abrego Garcia and four other individuals in a Home Depot parking lot. The officers noted that one of the men with him was already a validated MS-13 gang member in their database. The encounter was documented on a gang field interview sheet, which remains a common investigative tool used nationwide.
Applying the California-style validation criteria, investigators noted:
- Affiliation: Abrego Garcia was contacted in the company of a validated MS-13 member (criterion 4).
- Dress and appearance: He wore clothing consistent with local MS-13 identifiers — blue and white apparel and a “13” belt buckle (criterion 7).
- Reliable source: A vetted informant had previously identified him as a ranked member of MS-13 (criterion 3).
- Tattoos: He displayed visible “MS”-style hand tattoos recognized by local investigators (criterion 8).
Garcia met four of eight validation criteria. In many jurisdictions, that combination — association, reliable source, attire and tattoos — is enough to classify someone as a confirmed gang member.
What makes this case relevant now is the scrutiny such classifications face in today’s legal and political climate. In an era where deportations, sanctuary policies and federal-state coordination draw headlines, any agency’s gang documentation can quickly become part of a national debate. Defense attorneys now challenge validation forms line-by-line, looking for outdated criteria, lack of corroboration, or bias. Prosecutors must be able to show that every checkmark on that form is backed by verifiable evidence.
Modern investigators also have digital tools that didn’t exist even five years ago: open-source intelligence, geolocation data and social-media analysis often supplement traditional criteria like clothing and tattoos. However, technology doesn’t replace fundamentals. The totality-of-circumstances approach still applies — multiple converging factors, not one snapshot, determine classification.
If initiation status is uncertain or predicate crimes haven’t been established, investigators can and should classify an individual as an associate rather than a full member. That distinction remains crucial in 2025, when agencies face increased transparency demands, public-records requests and social-media amplification of perceived misidentifications.
The Abrego Garcia case reminds us that accurate documentation, corroborated sources and local expertise are what keep gang classifications defensible — both in court and in the court of public opinion.
Understanding local context in tattoo analysis
Media coverage often misinterprets gang tattoos. The only people truly qualified to assess their meaning are actual gang members or local gang investigators familiar with area-specific symbols.
For example, in my jurisdiction some Norteño members have “3200” tattoos, representing the 3200 block of a local street they claim as turf. Others display “SK,” meaning “Scrap Killer,” referring to rival Sureños.
In another town, “3200” or “SK” might mean nothing — or something entirely different. Context is everything. You rarely see someone tattoo “MS13” across their chest; that’s the equivalent of wearing a concert T-shirt with the band’s name — it attracts unwanted attention.
Building better gang cases
Accurate classification strengthens prosecutions, enhances officer safety and prevents wrongful identification. Gang investigators must continually refine their understanding of local groups, maintain professional skepticism and rely on evidence, not assumptions.
For additional guidance, see my book “The Street Crimes Handbook, 2nd Edition,” which covers how to put together strong gang cases, drug sales, illegal gun possession and human trafficking investigations. Read an excerpt here.
Training discussion points
- How can agencies ensure consistency and fairness in gang classification?
- What documentation safeguards help defend gang member identifications in court?
- How should investigators distinguish between members and associates?
- What strategies help identify new or emerging gangs before they grow violent?
Tactical takeaway
When classifying gang members, document multiple validation criteria and base your findings on evidence, not assumptions. Accuracy protects both the case and your credibility.
How does your agency review or update its gang validation criteria to keep up with changing laws and gang trends? Share below.
