Haley Nelson began her career as a Special Agent at the South Carolina Law Enforcement Division (SLED) in 2012 assigned to the Crime Scene Unit. During her tenure in Crime Scene, she provided technical assistance to city, county, and federal jurisdictions in the processing of violent crime scenes and expertise in bloodstain pattern analysis, shooting reconstruction, and crime scene reconstruction.

Nelson was selected to join the Behavioral Science Unit in 2016. She received specialized training in all areas of criminal behavior and has participated in complex investigations to include threat assessment and management, stalking, homicide, sexual assault, arson, linkage analysis, and crimes against children. In October of 2020, Nelson successfully completed the understudy program for the ICIAF and became certified in criminal investigative analysis. In August of 2022, she was promoted to Lieutenant where she continues to carry a caseload, oversees the unit, and provides training.

Nelson also serves in a support role as a hostage negotiator for the SLED SWAT Team. She has testified as an expert in South Carolina court systems in the areas of crime scene investigation, bloodstain pattern analysis, shooting reconstruction, crime scene reconstruction, and threat assessment and management. In July of 2022, Nelson was awarded a Letter of Commendation from SLED for her role in investigating a 1976 homicide that lead to an arrest and conviction.

Nelson attended West Virginia University where she earned a Bachelor of Science degree in Forensic and Investigative Science and Bachelor of Arts degree in Criminology.