The death of a young Layton woman last month will apparently remain unexplained, with the state medical examiner unable to determine a cause of death and the police department closing the case.

Lisa C. Workman, 24, was found dead in her apartment Sept. 14 by a relative. Layton police began an investigation because the death was unattended and, finding bruises on her neck, they considered it a possible homicide.But State Medical Examiner Todd Grey has not been able to pinpoint a cause of death. The neck bruises were not significant, and he ruled out strangulation or suffocation.

Medical and toxicology tests ruled out drugs, alcohol, poison and any forms of violence, Grey said. Police reviewed Workman's medical records and found no evidence of illness, depression or other problems.

Grey said it is not too unusual to be unable to determine a cause of death, even in young people.

Medical examiners suspect a heart problem such as arrhythmia, or irregular heartbeat, triggered by an unknown cause could be the culprit. The arrhythmia would leave no trace that can be found in an autopsy, he said.

Grey said about 3 percent of autopsies reveal no specific cause of death.

Layton detective Jim Andrews said no suspect was determined in the case, and with the medical examiner's report, the case will be ruled a natural death.