Trusted Security Guard Services for Maryland, D.C., and Pennsylvania
Family-owned and led by a seasoned law enforcement professional, Defender One delivers reliable, responsive contracted security guards tailored to your needs.
We Care About Your Safety
Defender One Security delivers trusted, comprehensive security solutions across Maryland, Washington, D.C., and Pennsylvania. Founded in 2009 by Baltimore native Jon Krieger, the company remains proudly family-owned and operated.
With more than 30 years in law enforcement—including leadership roles in patrol, internal affairs, traffic, and community outreach—Jon launched Defender One to bridge the gap between private security and public safety. That same commitment to professionalism, accountability, and community still drives the company today.
As a family-run business, Defender One offers a level of personal service and responsiveness national firms often can’t match. Jon and his wife Jennifer oversee daily operations, working directly with clients to ensure every detail is handled with care and integrity.
Trusted Security Solutions Since 2009
Decades of experience, grounded in law enforcement leadership and a commitment to professionalism you can count on.
Highly Trained Security Guards
Our team is made up of skilled, vetted security guards trained to deliver preventative, site-specific protection.
24/7 Coverage and Peace of Mind
We provide around-the-clock security through contracted services—ensuring consistent presence, not reactive response.
Family-Owned, Personally Committed
We’re not a faceless franchise. Every client matters, and every detail is handled with care by our leadership team.
Don’t leave safety to chance. Work with a team that treats it like a priority—because it is.
Our Comprehensive Security Services
Reliable Security Presence for Your Property
Uniformed security professionals stationed at your facility to deter threats, safeguard property, and ensure a safe environment. Ideal for corporate offices, retail, schools, healthcare facilities, and more.
Executive and Personal Security You Can Trust
Whether you need discreet protection for an event or long-term security for high-profile individuals, our team delivers peace of mind with professionalism and discretion. Transportation services available.
Fast, Professional Fingerprinting for Individuals & Teams
Efficient fingerprinting for employment, licensing, compliance, and more. Available for individuals or coordinated group sessions. Walk-ins accepted Monday-Friday9:30 AM – 4:30 PM.
From Our Clients
Defender One is an incredible company to work with. Their security team is professional and pleasant to work with. I have seen members of their team deal with a variety of emergencies and all were handled efficiently and had great outcomes. I feel completely safe working with Defender One and I am so thankful they are here to protect us.
Provides excellent, expert services for our organization.
We love Defender One! They always do an excellent and professional job for our organization! Thank you once again for keeping our community and members safe.
It was a pleasure using Defender One for our security needs. They were very professional and punctual. I highly recommend Defender One for ALL your security needs
News & Resources
Top Five Overlooked Vulnerabilities — and What You Can Do About Them
In the realm of security, many risks are obvious: unlocked doors, inadequate lighting, or inattentive personnel. But often, it’s the vulnerabilities we don’t see or don’t think about that lead to the greatest exposures. At Defender One Security, with decades of law...
An Overview of Unarmed Security Solutions
In today’s evolving security landscape, not every environment needs an armed presence to ensure safety and order. In fact, nearly three‑quarters; about 73.7% of all security guard positions are staffed by professionals working in investigation and security services,...
Armed vs. Unarmed Security: What’s Right for Your Property?
Choosing between armed and unarmed security depends on your property’s risks, environment, and budget. This guide breaks down the differences, benefits, and key factors so you can make an informed decision about the right level of protection for your people and assets.
An Overview of Armed Security Solutions
Armed security services provide highly trained officers equipped to protect people, property, and high-value assets in high-risk environments. From financial institutions and healthcare facilities to critical infrastructure and major events, armed guards deliver deterrence, rapid response, and professional presence. This guide explains when to consider armed security, the training and certifications required, and how to choose the right provider for your needs.
Schools Need Security Drills Beyond Fire Alarms
Fire drills are a long-standing tradition in schools, ensuring students know how to evacuate safely. However, schools need security drills beyond fire alarms to address modern threats effectively. Schools face risks that range from active threats to medical crises and...
Protecting Executives from Cyber and Physical Threats
A CEO’s influence extends far beyond boardrooms. Their decisions move markets, their visibility invites scrutiny, and their digital footprint exposes vulnerabilities. From cybercriminals seeking financial gain to physical threats like stalking, executives are prime...
