Police in Lambeth have launched an appeal for information following the death of two men after they collapsed in a sauna in Waterloo.
Police were called by ambulance crews to the Pleasuredrome sauna under the railway arches in Cornwall Road at about 8.15am on Saturday morning.
A 39-year-old man was was pronounced dead at the scene. A post-mortem examination failed to establish a cause of death.
Another man, aged 46, was taken to hospital where he died on Monday.
A third man, aged 34, was taken to hospital for treatment and discharged on Monday evening.
Detectives are treating both deaths as unexplained.
Police are appealing for a man seen entering the venue with the first victim to come forward as soon as possible.
He is described as a white man aged 25-35 with brown hair and a goatee beard approximately 6 ft tall with a slim build.
Lambeth CID are keen to identify and trace this man as officers have concerns for his welfare. Any information in connection with this investigation will be treated with the strictest confidence.
Anyone with information or witnesses are asked to Lambeth CID on 020 8721 3597 or Crimestoppers on 0800 555 111.