Master Deputy Jillian Olson, 29, had served with the Lexington County Sheriff’s Department since 2021.
LEXINGTON, S.C. — A Lexington County sheriff’s deputy died Thursday during an underwater dive-team training session on Lake Murray, prompting investigations by state authorities and the county coroner, the Sheriff’s Department said.
Master Deputy Jillian Olson, 29, was participating in training with the department’s dive team when the incident occurred July 30. Officials had not released details about what happened beneath the water or what led to her death as of Sunday. The Lexington County Coroner’s Office is working to determine the cause and manner of death.
The South Carolina Department of Natural Resources is leading the broader investigation, with assistance from the South Carolina Law Enforcement Division. The state Department of Natural Resources also led the recovery effort through its Investigations Unit and Aquatics Investigation and Recovery team, according to published reports. Several public-safety agencies responded to the lake.
Lexington County Sheriff Jay Koon said Olson was a valued member of the department who showed a strong commitment to public service. He said her work made a difference both inside the agency and in the community.
“Jillian exemplified commitment and service,” Koon said in a department statement. “She faithfully carried out her duties and selflessly worked to make those around her better.”
Olson began her career with the Lexington County Sheriff’s Department in 2021. She worked as a patrol deputy for more than a year before transferring to a position serving warrants. The department promoted her to master deputy in its Warrant Division in 2025. She had served on the dive team since 2024 and had completed more than 100 hours underwater, according to officials.
The Lexington County Sheriff’s Foundation named Olson its outstanding judicial services deputy of the year during an awards banquet last spring. The department said she received the honor after independently developing reference guides and document templates for judicial services deputies. Officials said the materials improved training and helped the division operate more efficiently.
Olson also received the department’s tactical operations support award in 2023. She was scheduled to receive a five-year honorable service award in August, recognizing the anniversary of her work with the agency.
“Jillian’s dedication to her community and department is well-documented with awards and recognitions,” Koon said. “She’ll be most remembered for what she did with no fanfare. Her decision to join our dive team is just one example of her going above and beyond.”
A native of Illinois, Olson graduated from Western Illinois University in 2019 with a bachelor’s degree in law enforcement and justice administration. She completed a master’s degree in student personnel services at the university in 2021 before beginning her career in Lexington County.
Koon thanked the state and local agencies that assisted the department after Olson’s death. He also praised the Department of Natural Resources, the State Law Enforcement Division and the coroner’s office for handling the investigation with care.
Authorities had not announced how long the investigations might take or whether preliminary findings would be released. The official cause and manner of Olson’s death remained pending as of Sunday.
Author note: Last updated August 2, 2026.