Police are investigating if the drug GBL led to the death of two people in separate incidents in Birmingham at the weekend.
Police were called to the Roundabout, in Northfield, on Saturday night following a call from ambulance crews, who were treating three people who needed urgent medical help.
A 28-year-old woman was found collapsed at the scene and received emergency treatment, but later died in hospital.
A post-mortem is due to take place to establish the cause of death.
Two other men were also found collapsed at the address and were also taken to hospital for emergency treatment. Both have now been discharged.
Officers believe there may have been a number of people at a party during the evening and are appealing for anyone with information to contact police.
Following a number of statements taken, police are investigating whether a controlled substance, known as GBL, was taken by members of the party.
Police are also investigating the death of a man in a separate incident on Saturday in Birmingham city centre.
The 24-year-old was found dead an address in Brindley Drive, Birmingham, at around 1.15pm. A post-mortem and toxicology tests are due to take place.
Detective Inspector Andy Hawkins, from Force CID, said: "A post-mortem, including a toxicological examination, will be undertaken to establish the cause of death in both incidents. We are appealing for anyone with information to contact us."
He said: "We believe that the controlled substance Gamma-Butyrolactone, or GBL, the base solvent to a number of alloy wheel cleaners, super glue removers and paint strippers, may have been used as a drug at the gathering at the address in Northfield.
"We are appealing for anyone who may have any information to contact us."
Barry Eveleigh, Lead Commissioner for Drug Treatment for the Birmingham Drug and Alcohol Action Team, said: "GBL is a dangerous drug, closely related to GHB.
"Taking GBL or GHB puts users at significant risk of unconsciousness, coma or even death.
"As both drugs have a sedative effect and can make users feel very sleepy, they have also been linked to drug assisted sexual assault."
GBL is closely related to the banned substance GHB (gamma-hydroxybutyric acid). Once GBL is consumed, the body converts GBL to GHB which leads to dizziness, nausea, vomiting, headache, sore throat, confusion, numbness and blurred vision. GBL can be found in nail varnish and alloy wheel cleaner and is a Class C drug. It is still legal, but there are restrictions. GBL is a chemical that has widespread legitimate uses (for example, in nail polish, paints and as industrial solvents) but are also misused. It is of the Class C drug gamma-hydroxybutyrate (GHB), meaning that when either substance is ingested it is rapidly converted to GHB.