A sixth suspected drug-related death since the weekend has been identified by police investigating the sale of Class A drugs in Essex.
A woman in her 30s found dead in Southend on Sunday is now part of the investigation, Essex Police said.
It follows the deaths on Monday and Tuesday of two other women and three men, all within a six-mile (10km) radius.
One has been named as Cian Daly, 20, from Leigh-on-Sea.
Mr Daly's relatives said they did not want to comment until they had more information about the police investigation.
A friend, who did not want to be named, described Mr Daly, who was found dead on Monday, as a "great friend who didn't have a bad bone in his body".
More than £2,000 has been raised by friends towards a memorial bench in a local nature reserve, and to support the family.
On Tuesday, a man and woman in their 40s on Canvey Island, and a man in his 20s in Benfleet, were found dead. A woman in her 30s was found on Monday in Westcliff-on-Sea.
Tests are being carried out to identify the substance or substances involved in the deaths.
Ch Supt Kevin Baldwin said it was too soon to say if drugs were smoked, injected or taken as pills.
"All of the deaths occurred in their own homes, which is an unusual element because your own home is normally a safe environment and the circumstances suggest that they weren't able to call for assistance," he said.
Rebecca Harris, MP for Castle Point, which covers Benfleet and Canvey Island, said police were taking the deaths "incredibly seriously".
"We hope this is an isolated incident and it's not a wider problem," she said.
"We don't want any more families to lose loved ones, because this must be devastating for [those] families in south Essex."
The force has urged anyone with information about the sale of Class A drugs in the county to contact them.