LAS VEGAS — The mother of a Las Vegas police officer and U.S. Army veteran who was among the 58 people killed in the worst mass shooting in modern U.S. history died during the weekend, after his memorial service.

Clark County Coroner John Fudenberg (FYOU’-den-berg) said Wednesday that Sheryl Stiles died Sunday at Sunrise Hospital and Medical Center, after family members said she collapsed Friday on an escalator at the South Point hotel in Las Vegas.

She was 56 and lived in Louisville, Kentucky.

The coroner says her cause of death will be determined by examinations and tests.

Her brother, Lewis Stiles, told KVVU-TV Fox 5 that his sister had been in Las Vegas for memorials to Charleston Hartfield.

He was killed in the Oct. 1 shooting at an open-air music concert on the Las Vegas Strip.