West Mercia Police is examining new evidence relating to the death of Tasha Ashby in Hereford in 2023.
The incidents in Somerset have prompted a call for a debate around the checking of drugs.
Suspicions were raised when Glenn Ford said he had travelled to the Isle of Man to play golf for the day.
Two areas of Edinburgh's Old Town have been identified as potential sites for the facility - Spittal Street and an area around Cowgate.
Abidul Islam and Mohammed Sajid are jailed for more than five years each at Sheffield Crown Court.
A BBC investigation shows how nitazene deaths have risen and the illegal drug market is changing.
Ryan King was part of an organised crime group that tried smuggling cocaine and heroin into the UK.
The efforts, part of Operation Scorpion, saw five forces team up to seize large amounts of drugs.
Samuel Coker would target "vulnerable residents" and take over their homes as a base for dealing.
