In a Durham Sheriff's Office investigation report released Thursday, Merck's head of global security told deputies that a noose was first found by construction workers returning from lunch around 11:30 a.m. on May 24. The incident was not reported to Merck officials until three days later and was not reported to campus security until June 3.
Authorities said a second noose was reportedly found in a different location at the same construction site on Monday.
Merck operates a 262-acre facility in north Durham. The News & Observer reports that a contractor on site found "a rope fashioned as a noose" at a construction project, according to an email obtained by the newspaper.
The Durham site was one of two Merck plants tapped to help manufacture the Johnson & Johnson COVID-19 vaccine earlier this year.
The Associated Press contributed to this report.