A third man has died of a suspected drug overdose in Darlington, as police said they no longer believe a "bad batch" of heroin was to blame.
Two men - one in his late 40s and one in his late 20s - were found dead at their homes in the North Road area of the town on Saturday.
A third, in his 30s, was left in a critical condition and has died.
Police initially said a "bad batch" of heroin was thought responsible, but now suspect the men died of overdoses.
Two women have been arrested on suspicion of supplying Class A drugs in connection with one of the deaths.
Det Insp Andy Crowe said: "Following our investigations over the weekend, we no longer believe these deaths are as a result of a 'bad batch' of heroin, but each case is a separate tragedy."