A breakthrough in that drugs theft from a Nelson pharmacy Sunday.
A 26 year old woman has been arrested and faces charges of Break and Enter.
Nelson Police Sgt Dino Falcone says the drugs have not been found.
A variety of narcotics were stolen including the potent and potentially lethal heroin substitute that is becoming established in certain circles.
Police are repeating their public warning that use of the stolen drugs could lead to serious harm or even death.
Falcone says video surveillance was key to the arrest.