Two people who helped police in a drugs raid are being called on to come forward.
Officers were carrying out the operation at an address in Firle Road, Eastbourne, on May 22.
At 10.50am officers went into the house and two men were arrested on suspicion of supplying drugs.
A woman fled outside but was detained by a plain-clothes officer and later charged with the same offence.
As the officer walked her back, a man and a woman in a small blue hatchback car pointed out a package apparently thrown from a window at the property.
This was recovered and found to contain a large amount of what are thought to be Class A drugs - heroin and crack cocaine. These are being forensically tested.
Detective Constable Steve Shimmons, of Eastbourne CID, said: "Unfortunately, the two people who had spotted the package drove off shortly afterwards.
"We are very keen to speak to them and would ask that they, or indeed anyone else who may have relevant information, get in touch as soon as possible.
"They should phone Sussex Police on 101 or email email@example.com, quoting serial 318 of 22/5."