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Axon·Software Engineer·Onsite - System Design / Architecture·Senior

Senior
May 2026

Summary

Axon Research Engineer interview, second session, focused entirely on a system design problem for law enforcement video intelligence. No behavioral questions, no warmup, just straight into a gnarly open-ended design problem that took the full session.

Questions Asked (1)

Q1

Design a video intelligence system for law enforcement that ingests footage from body cameras, CCTV, dashcams, interview rooms, drones, and uploaded evidence clips. The system should let investigators search across massive archives, reason over footage, and surface evidence-relevant moments rather than just summarizing video.

System DesignTechnical Trade-offsProduct Sense & Ideation
Author's notes

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints, then design a scalable, multi-modal pipeline that ingests diverse video sources, extracts rich metadata and embeddings, and enables semantic search and reasoning over footage. Focus on the unique challenges of law enforcement: data sensitivity, chain of custody, and the need to surface evidence-relevant moments rather than just summaries.

Pro tip: Emphasize the importance of a human-in-the-loop approach and explainability, as law enforcement decisions require transparency and accountability. Also, discuss how you would handle false positives and ensure the system augments, rather than replaces, investigator judgment.

1. Clarify Requirements and Constraints

Ask questions to understand scale (e.g., petabytes of video, number of concurrent users), latency needs, data retention policies, and legal/compliance requirements (e.g., chain of custody, privacy). Identify key use cases such as searching for a person, object, or event across multiple video sources.

2. Design Ingestion and Processing Pipeline

Outline a scalable ingestion layer that handles diverse formats and sources, with preprocessing steps like transcoding, frame extraction, and metadata tagging. Incorporate computer vision models for object detection, action recognition, and face recognition (with privacy safeguards), and generate embeddings for semantic search.

3. Architect Storage and Indexing

Propose a storage solution that balances cost and access speed, such as object storage for raw video and a vector database for embeddings. Design an indexing strategy that supports fast similarity search and filtering by metadata (time, location, camera type).

4. Enable Search and Reasoning

Describe how investigators can query the system using natural language or example clips, and how the system retrieves and ranks relevant moments. Include a reasoning layer that can correlate events across multiple videos and surface evidence with explanations.

5. Address Security, Privacy, and Scalability

Discuss access controls, encryption, audit logs, and compliance with regulations like CJIS. Explain how the system scales horizontally and handles failures, and how it ensures low-latency search over massive archives.

Key Points to Mention

  • Multi-modal indexing: combining visual embeddings, audio transcripts, and metadata for robust search.
  • Scalable ingestion using message queues and distributed processing (e.g., Kafka, Spark).
  • Vector databases (e.g., FAISS, Pinecone) for efficient similarity search over video embeddings.
  • Chain of custody and audit trails to ensure evidence integrity and admissibility.
  • Human-in-the-loop verification and explainable AI to build trust and reduce false positives.
  • Privacy-preserving techniques like face blurring or on-device processing for sensitive data.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.