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
Security That Knows Your Facility’s Culture
A Campus That Runs on Familiarity The Jewish Community Center of Greater Baltimore (JCC) campus is events-driven, with multiple desks running at once on any given day. For most of the year, two armed guards cover the site, one posted at the school entrance and one at...
Management Makes A Difference
A Portfolio That Doesn't Leave Room for Error After decades of working with security providers of every size, the team at David S. Brown knows what a lot of property managers eventually learn the hard way: with security, you get what you pay for. The cheapest security...
Preparing for the High Holidays: A Security Checklist for Your Congregation
High Holiday Preparedness Rosh Hashanah and Yom Kippur bring some of the fullest sanctuaries of the year. Parking lots fill up faster. Guest lists grow. Services run longer, and routines that work fine on a quiet Saturday get tested in ways they don't the rest of the...
Is Your Security Guard Asleep on the Job? Here’s What It Really Means
Your Guard Was Sleeping. Why Haven't You Changed Providers? It happens more than the security industry likes to admit. A manager walks the floor, checks a monitor, or steps outside — and finds their security guard asleep on post. Maybe it's happened to you. Maybe it...
The High Cost of Waiting: Why Delaying Security Decisions Can Put Your Organization at Risk
There's a particular kind of logic that takes over during uncertain times. It sounds responsible. Careful. Financially disciplined. "Let's wait." Wait until budgets stabilize. Wait until there's more clarity. Wait until something actually happens. For many...
Is Your Child Protected?
You’ve checked the schedule, met the staff, and read the reviews. But there’s one question most parents don’t ask: If something unexpected happened, would anyone be ready? Most environments that serve children are built with good intentions. They’re designed to be...