FAIRVIEW HEIGHTS, Ill (KMOX) - Fairview Heights police have a mystery on their hands following the death of a 20-year-old woman.

First responders who arrived at 20 Kassing Drive early Sunday found Jennifer Herling of Collinsville lying unconscious.

She died a short time later at a nearby hospital.

Police are awaiting toxicology test results and talking to several other people who were inside the home at the time to try and figure out what happened.

Earlier this year, 30-year-old Jessica Williams died of a drug overdose in that same home in Fairview Heights.

Williams, of Collinsville, went missing March 8. Her body was discovered weeks later in Washington Park.

Douglas W. Oliver II, 46, and Deborah A. Perkins, 55, of 20 Kassing Drive, were charged last month with concealment of a homicidal death.