Information Systems Security Engineer

Markon is seeking an experienced Systems Engineer specializing in Information Systems Security Engineering (ISSE) and Data Engineering to support an Intelligence Community client in Chantilly, Virginia. This position will design, secure, integrate, and optimize mission-critical cloud and data solutions within classified environments, combining systems engineering principles, cybersecurity compliance, advanced analytics, and modern data engineering practices. The Systems Engineer will work across secure cloud architectures, ETL pipelines, graph databases, and AI/ML-supporting technologies to deliver scalable, compliant solutions aligned with mission requirements.

• Lead Information Systems Security Engineering (ISSE) activities throughout the system lifecycle, including security architecture development, security control implementation, and compliance with NIST and Sponsor-specific requirements.

• Develop and maintain Assessment and Authorization (A&A) documentation supporting Authorization to Operate (ATO), including System Security Plans (SSPs), Plans of Action and Milestones (POA&Ms), test procedures, and continuous monitoring artifacts.

• Conduct security scans, vulnerability assessments, patch management, and remediation activities across classified cloud and on-premises environments.

• Integrate security-by-design principles into system architectures, data flows, ETL pipelines, and operational workflows.

• Design, develop, and optimize Extract, Transform, Load (ETL) pipelines supporting enterprise data integration, advanced analytics, and AI/ML initiatives.

• Develop and maintain Neo4j graph database solutions, including data modeling, relationship mapping, schema optimization, and Cypher query development.

• Clean, preprocess, analyze, and visualize medium-to-large datasets to support mission analysis and operational decision-making.

• Develop secure software components using technologies such as Cypher, Python, Java, and JavaScript.

• Perform technical and functional assessments, risk analysis, cost estimation, trade studies, and systems engineering evaluations.

• Support secure cloud architectures, virtualization technologies, and scalable data solutions within mission environments.

• Collaborate with systems engineers, developers, security teams, and mission stakeholders to ensure solutions meet technical, accreditation, and operational requirements.

• Participate in Agile development activities, including sprint planning, iterative development, and CI/CD processes.

• Maintain comprehensive documentation covering technical requirements, data models, engineering decisions, software components, and security compliance.

Required:

• Active TS/SCI clearance with Full Scope Polygraph (FSP).

• Bachelor's degree and at least 8 years of relevant experience, including 2 years of Sponsor experience; OR

  • Master's degree and at least 6 years of relevant experience, including 2 years of Sponsor experience; OR

  • PhD and at least 3 years of relevant experience, including 2 years of Sponsor experience.

  • An additional 4 years of relevant experience may be considered in lieu of a degree.

• Demonstrated experience designing, securing, and maintaining data flow solutions within classified or high-security environments.

• Strong ISSE experience, including security architecture, A&A/ATO processes, vulnerability management, accreditation documentation, and continuous monitoring.

• Hands-on experience developing ETL pipelines, data models, activity models, and data engineering solutions supporting AI/ML initiatives.

• Proficiency in at least one programming language, such as Cypher, Python, Java, or JavaScript.

• Experience with graph database technologies, with Neo4j and Cypher expertise preferred.

• Experience cleaning,…