The deaths of two men found at the same property may be linked to an illegal psychoactive drug, detectives believe.
Warwickshire Police issued a picture of packaging being assessed as part of the inquiry into the deaths in Rugby, and warned anyone suffering unusual symptoms to seek immediate medical help.
Officers were called to an address in King Edward Road, Rugby, by West Midlands Ambulance Service at around 6.40pm on Sunday.
Two men, both in their 20s, were pronounced dead at the address, and officers are now awaiting the results of post-mortem examinations and toxicology tests.
Detective Sergeant Mark Greaves said: "Forensic examinations are still being carried out but we are releasing an image of packaging and officers want to raise awareness of the dangers to anyone who may be using drugs from a similar packet either in Rugby or the wider Warwickshire area.
"If you experience any unusual symptoms after taking drugs, please seek medical attention immediately."
Anyone with any information or knowledge of the packaging, or its origin, is asked to contact police on 101.