Officials are investigating after an inmate at the Weld County Jail died in custody overnight, the Greeley Police Department announced.

Police said the inmate, 41-year-old Amy Cross, was found in medical distress at 11:30 p.m. Saturday. On-site medicinal staff began life-saving efforts, but she died just after midnight Sunday.

The cause of Cross’s death is unknown, police said. It is unclear what happened leading up to the medical distress or where she was found.

Cross was arrested on June 27 for criminal impersonation and attempt to influence the public, according to jail records. She had been in and out of custody since 2016 on charges including car theft, identity theft and parole violation.

The Weld County coroner’s office is currently conducting an autopsy and running lab tests to determine Cross’s cause and manner of death, police said.

The 19th Judicial Critical Incident Response Team is investigating the death.

No additional details are available pending the investigation, police said.