Senior Machine Learning Engineer III

Are you passionate about building trustworthy Generative AI solutions that deliver accurate, source-grounded results? Do you enjoy solving complex retrieval and search challenges while shaping the next generation of AI-powered legal and professional technology? About our Team LexisNexis Legal & Professional, which serves customers in more than 150 countries with 11,800 employees worldwide, is part of RELX ( ), a global provider of information-based analytics and decision tools for professional and business customers. Our company has been a long-time leader in deploying AI and advanced technologies to the legal market to improve productivity and transform the overall business and practice of law, deploying ethical and powerful generative AI solutions with a flexible, multi-model approach that prioritizes using the best model from today’s top model creators for each individual legal use case. The company employs over 2,000 technologists, data scientists, and experts to develop, test, and validate solutions in line with RELX Responsible AI Principles ( ). About the Role We are seeking an AI Engineer focused on Retrieval-Augmented Generation (RAG) to help design, build, and optimize AI-powered experiences. In this role, you will contribute to the development of retrieval systems, evaluation frameworks, and source-grounded Generative AI solutions that enable users to access trustworthy and relevant information. You will work with advanced AI technologies while helping ensure quality, accuracy, and responsible AI practices. Responsibilities Design, build, and optimize Retrieval-Augmented Generation (RAG) applications. Develop and manage document ingestion, chunking, embedding generation, retrieval, reranking, and source-grounded response workflows. Design and operate vector search solutions using modern vector database technologies. Validate retrieval quality, citation accuracy, relevance, coverage, and factual grounding using reproducible evaluation datasets. Collaborate with cross-functional teams to improve response quality and reduce hallucinations. Implement hybrid search strategies combining keyword, metadata, semantic/vector search, and reranking techniques. Monitor and evaluate retrieval performance, latency, cost, and AI system quality. Support the development of scalable and responsible Generative AI solutions across legal and professional information products. Requirements Hands-on experience with Retrieval-Augmented Generation (RAG) applications, including document ingestion, chunking, embedding generation, retrieval, reranking, and source-grounded responses. Strong understanding of Generative AI and LLM capabilities, limitations, hallucination mitigation, and response-quality evaluation. Experience designing and operating vector search solutions using Qdrant, Pinecone, pgvector, LanceDB, OpenSearch vector search, or equivalent technologies. Ability to validate retrieval quality, citation accuracy, relevance, coverage, and factual grounding using reproducible evaluation datasets. Preferred Qualifications Experience building AI agents or multi-step workflows with tool use, memory, and human review. Familiarity with agentic and LLM frameworks such as Google ADK, LangChain, LiteLLM, or MCP. Experience with hybrid search strategies combining keyword, metadata, semantic/vector search, and reranking. Experience applying RAG or Generative AI to legal, financial, publishing, or other highly regulated content domains. Knowledge of LLM observability, including monitoring latency, cost, retrieval performance, and unsafe or unsupported outputs. Work in a Way That Works for You We promote a healthy work/life balance across the organisation. We offer an appealing working prospect for our people. With numerous wellbeing initiatives, shared parental leave, study assistance and sabbaticals, we will help you meet your immediate responsibilities and your long-term goals. Working Pattern Working flexible hours - flexing the times when you work in the day to help you fit everything in and work when you are the most productive. About the Business LexisNexis Legal & Professional® provides legal, regulatory, and business information and analytics that help customers increase their productivity, improve decision-making, achieve better outcomes, and advance the rule of law around the world. As a digital pioneer, the company was the first to bring legal and business information online with its Lexis® and Nexis® services. We know your well-being and happiness are key to a long and successful career. We are delighted to offer country specific benefits. Click here to access benefits specific to your location. We are committed to providing a fair and accessible hiring process. If you have a disability or other need that requires accommodation or adjustment, please let us know by completing our Applicant Request Support Form or please contact 1-855-833-5120. Criminals may pose as recruiters asking for money or personal information. We never request money or banking details from job applicants. Learn more about spotting and avoiding scams here . Please read our Candidate Privacy Policy . We are an equal opportunity employer: qualified applicants are considered for and treated during employment without regard to race, color, creed, religion, sex, national origin, citizenship status, disability status, protected veteran status, age, marital status, sexual orientation, gender identity, genetic information, or any other characteristic protected by law. USA Job Seekers: EEO Know Your Rights .