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
Who Provides Short-Term Security After a Threat to Staff?
Imagine getting a call that stops you in your tracks. Someone has made a threat toward one of your employees. Maybe it’s a physician. Maybe it’s a member of leadership. Either way, it’s serious enough that people are uneasy and you’re trying to figure out what to do...
Why More Schools Are Hiring Professional Security Guards
The Growing Need for Specialty-Trained Security Guards at Schools Schools today face a unique challenge: how to create a learning environment that feels open and welcoming, while still maintaining the level of safety students, teachers, and families expect. As...
What Does a Security Guard Do for Clients?
Daily Responsibilities and Duties Explained When people think about a security guard, they often picture someone standing at a door or walking rounds on a property. In reality, professional security guards play a much broader role in protecting people, property, and...
8 Steps to Building a Stronger Security Program
Whether you manage an office, school, hospital, or apartment community, having a formal security program is no longer optional—it’s essential. A structured plan protects your people, property, and reputation while helping your team respond quickly when incidents...
Top 5 Reasons to Be Thankful for a Reliable Security Partner
Reliable security is one of those things that often goes unnoticed until it’s tested and that’s when the value of a trusted partner really shows.
Defender One believes dependable protection is more than a service; it’s a commitment to your safety, confidence, and calm. Below are the five most common benefits we hear from our clients on why they are grateful for partnering with us.
Top 3 Reasons Clients Switch to Defender One
As security needs grow more complex, many organizations are turning to Defender One for dependable protection and personalized service. Here are the top three reasons clients make the switch—and why you might too.1. Personalized, Client-First Approach (vs....
