By Alex Sappok, Ph.D.
Mail security in correctional facilities represents a critical challenge for administrators nationwide. While digital correspondence has reduced risks in general mail, special mail categories — such as legal, business, religious and media correspondence — remain vulnerable pathways for contraband. The Texas Department of Criminal Justice (TDCJ) recently confronted this challenge head-on by implementing advanced terahertz (T-ray) imaging technology, establishing a new benchmark for security and interdiction in correctional settings.
The challenges facing correctional facilities have intensified in recent years, with contraband smuggling methods becoming increasingly sophisticated. TDCJ’s proactive approach demonstrates how innovative technology can address these evolving threats while maintaining the delicate balance between security imperatives and inmate rights. This case study examines the implementation, impact, and broader implications of T-ray technology advancement in correctional security.
The evolution of mail contraband challenges
Contraband smuggling through mail has evolved significantly, outpacing traditional detection methods. The increasing sophistication of smuggling tactics, including chemically treated paper infused with narcotics and other illicit substances, has heightened risks to staff, inmates, and overall institutional security.
Historical approaches to mail screening in correctional settings have typically relied on:
- Visual inspection
- Fluorescent lighting
- Basic X-ray technology
While effective against rudimentary smuggling attempts, these methods are less effective against modern concealment techniques. Smugglers have adapted by developing methods that are challenging for some traditional screening methods to detect:
- Microscopic application of synthetic cannabinoids to correspondence paper
- Soaking greeting cards in liquefied narcotics that dry invisibly
- Embedding thin strips of contraband within the seams of envelopes
- Creating false document watermarks containing illicit substances
- Using specialized inks with narcotic compounds that appear normal to the naked eye
A 2023 systemwide lockdown and search conducted by TDCJ exposed the vast scale of the problem:
- 3,021 instances of illegal drugs found on treated paper
- 584 cell phones hidden in incoming mail
- 587 weapons concealed in letters and small packages
- 75 gallons of alcohol detected through enhanced screening
- 564 other dangerous items, including electronic components and counterfeit documents
These findings underscored the urgent need for technological solutions that could match the evolving sophistication of contraband smuggling operations targeting correctional facilities.
The unique vulnerability of privileged mail
While general mail has been digitized to minimize security risks, legal and privileged correspondence must be physically handled to ensure attorney-client confidentiality. This requirement has made legal mail a prime target for contraband smuggling operations. A growing trend in “mail-back” schemes, where inmates manipulate outgoing legal mail to receive illicit materials upon return, has further complicated security measures.
The constitutional protection of privileged communication creates a particularly challenging security paradox for correctional administrators. Courts have consistently upheld inmates’ rights to confidential legal correspondence, limiting the extent to which such mail can be opened or inspected in the inmate’s absence. These legal constraints have created an exploitable security gap that traditional screening methods were not designed to fully address.
According to recent data from the National Institute of Justice, approximately 48% of contraband interceptions in U.S. correctional facilities now involve legal mail channels, highlighting the critical importance of finding solutions that can screen privileged correspondence without compromising legal protections.
The science behind T-ray technology
In response to these challenges, TDCJ launched a statewide deployment of T-ray imaging technology across 87 facilities and post offices, leveraging cutting-edge terahertz imaging to detect threats in real time.
Terahertz technology expands on the capabilities of traditional traditional screening methods, operating in the electromagnetic spectrum between microwave and infrared frequencies. This particular position in the spectrum gives T-rays unique properties that make them ideal for security applications:
- They penetrate most non-metallic materials, including paper, cardboard, clothing, and plastics
- They are non-ionizing, making them safe for operators and mail contents
- They can detect both metallic and non-metallic substances, including powders, liquids, and gels
- They provide real-time, dynamic imaging that reveals movement inside sealed packages
T-ray technology can detect all nine Department of Homeland Security-designated threats, including:
- Liquids (e.g., chemical agents, flammable substances)
- Powders (e.g., fentanyl, synthetic opioids, cocaine, methamphetamine)
- Chemically treated paper (e.g., K2, Suboxone-laced mail)
- Electronic components (e.g., SIM cards, miniature storage devices, contraband cell phones)
Amanda Flinn, TDCJ’s Assistant Director of Classifications and Records, highlights the importance of this innovation: “The saying is that iInk does not float,’ so if the scanner detects certain movements within the envelope, this could be cause for concern. It doesn’t necessarily mean it’s something bad. But if there is some type of fluid or powder in the envelope, it will need to be further examined.”
This dynamic imaging capability adds a new layer in mail security, allowing correctional officers to observe anomalous behavior within mail items that would remain completely invisible to traditional screening methods.
Implementation strategy and operational integration
The strategic placement of T-ray scanning devices within TDCJ has transformed the efficiency and effectiveness of mail screening. The technology is now used to inspect:
- Facility staff and warden correspondence
- Inmate legal mail
- Business and media correspondence
TDCJ’s implementation strategy involved a multi-phase approach to ensure optimal adoption and utilization:
- Pilot testing: Initial deployment at high-security facilities with documented contraband issues
- Technical training: Comprehensive instruction for mail room staff on equipment operation and threat identification
- Protocol development: Creation of standardized procedures for handling flagged items
- Scaling deployment: Systematic rollout across the entire TDCJ system
- Continuous assessment: Ongoing evaluation of effectiveness and refinement of screening protocols
The integration of T-ray technology into TDCJ’s existing security framework required careful consideration of workflow processes. Mailroom supervisors worked closely with technology providers to establish efficient screening protocols that minimized processing delays while maximizing detection capabilities. Staff reported that the intuitive interface and real-time imaging significantly reduced the learning curve typically associated with implementing new security technology.
Measurable impact on institutional security
This targeted approach has yielded immediate and quantifiable benefits:
1. Enhanced detection capabilities
T-ray screening offers non-invasive, high-resolution 3D imaging, allowing security personnel to see anomalies inside sealed envelopes without opening them. This capability has proven particularly valuable for screening legal mail, as it allows officers to detect potential contraband while maintaining the integrity of attorney-client privilege.
The system’s sensitivity to various substances has dramatically improved the facility’s ability to detect:
- Synthetic cannabinoids (K2/Spice) on paper at concentrations as low as 0.1mg
- Fentanyl and opioid compounds in powder form at microscopic levels
- Liquid narcotic solutions absorbed into paper products
- Electronic components as small as microSD cards concealed within documents
2. Reduction in contraband smuggling
Since deploying T-ray technology, TDCJ has observed a sharp decline in contraband-related incidents, particularly those involving chemically treated paper. The ability to detect previously undetectable substances has helped address important security vulnerabilities.
Internal TDCJ security assessments conducted six months after full implementation revealed:
- 78% reduction in drug-related disciplinary incidents
- 64% decrease in confiscations of chemically treated mail
- 53% reduction in suspected overdose incidents
- 41% decrease in violent incidents commonly associated with drug trafficking
These improvements have contributed significantly to a more stable institutional environment and reduced the resources needed to manage contraband-related incidents.
3. Operational efficiency gains
By automating and accelerating the screening process, correctional officers spend less time manually inspecting mail and more time focusing on high-risk anomalies. This efficiency gain has optimized resource allocation across facilities.
Before implementing T-ray scanning, TDCJ mail rooms typically processed approximately 120-150 pieces of legal mail per hour. With the new technology in place, processing capacity has increased to 250-300 pieces per hour — a productivity improvement of more than 100%. This enhanced efficiency has allowed TDCJ to:
- Reduce mail processing backlogs that had previously delayed legitimate correspondence
- Reassigning security personnel to other critical areas
- Improve documentation and tracking of suspicious items
- Implement more thorough secondary screening for flagged mail
4. Improved institutional trust & staff safety
The adoption of advanced screening technology aligns with TDCJ’s commitment to officer and inmate safety, reducing exposure risks for personnel handling potentially hazardous materials.
Correctional facilities nationwide have reported increasing concerns about staff exposure to dangerous substances, particularly synthetic opioids like fentanyl, which can cause serious harm through incidental contact. T-ray technology’s ability to detect these substances without requiring direct handling has significantly reduced occupational safety risks for TDCJ personnel.
Additionally, the technology’s objective screening process has helped address concerns about mail inspection fairness, contributing to improved institutional relationships with inmates and their legal representatives.
The future of mail security in corrections
TDCJ’s investment in T-ray technology serves as a national model for correctional mail security. As correctional institutions continue to face evolving threats, integrating advanced screening technology is no longer optional — it is increasingly viewed as essential.
Several state departments of corrections have initiated pilot programs with similar technology, seeking to replicate the security enhancements achieved in Texas. Industry analysts predict that T-ray screening will play a growing role in standard correctional screening practices within the next five years, potentially expanding to include:
- Integration with biometric identification systems
- Artificial intelligence-enhanced anomaly detection
- Database tracking of contraband patterns and trends
- Multi-spectral imaging capabilities
This commitment to innovation positions TDCJ at the forefront of correctional security, demonstrating how technological investment can yield significant returns in institutional safety and operational efficiency.
Key takeaways for correctional facilities nationwide
For institutions seeking to enhance their mail security infrastructure, TDCJ’s experience provides valuable insights:
- Invest in non-invasive screening: Advanced imaging reduces false positives and enhances contraband detection without opening legal mail.
- Train staff for optimal utilization: Ensuring correctional personnel fully understand and leverage new technology is crucial for maximizing security gains. TDCJ’s comprehensive training program included both technical operation and threat identification components.
- Adopt a layered security strategy: Combining T-ray technology with traditional measures, such as canine units and manual inspections, creates a comprehensive interdiction program. TDCJ found that integrating multiple screening methods created redundant security layers that significantly reduced vulnerability.
- Monitor and adapt to emerging threats: Contraband smuggling techniques will continue evolving. Institutions must remain proactive in updating their security protocols. TDCJ has established a dedicated intelligence unit that tracks smuggling trends and adjusts screening procedures accordingly.
- Balance security with legal requirements: Advanced technology offers a solution to the unique challenges posed by privileged correspondence, maintaining both security imperatives and constitutional protections.
As smuggling methods continue to evolve, correctional facilities must remain vigilant and adaptive. TDCJ’s experience suggests that combining cutting-edge technology with well-trained personnel and intelligence-driven security protocols creates the most robust defense against contraband threats. The department’s willingness to embrace innovation has not only enhanced its own security posture but has established a valuable model for the broader correctional community.
About the author
Alex Sappok, Ph.D., is the CEO of RaySecur, a company specializing in advanced security imaging technology. Before leading RaySecur, Sappok founded FST, Inc., an MIT spin-out focused on advanced RF sensing technology, which was later acquired by CTS Corporation (NYSE: CTS). He holds over a dozen patents and two R&D100 awards and has both S.M. and Ph.D. degrees in Mechanical Engineering from MIT, where he also held the Cummins-MIT Fellowship.