In opening its case, the Crown said Ms Chen had not gone for a walk on November 5, 2012, the night she disappeared.
Prosecutor Brian Dickey said it was most likely she was killed in her Torbay home.
But Mr Currie, who spent 25 years in the force, said one Waiau St resident had told police he had seen Ms Chen walking along the street and another potential witness came forward seemingly corroborating that statement.
"This sighting was completely ignored and the informant to this day has never been formally interviewed by the police," Mr Currie said.
Ms Chen's body was found in the Trias Reserve in Totara Vale 16 months after she disappeared.
Yesterday morning, police released a statement confirming they would not reinvestigate the case and were not looking for anyone else in connection with Ms Chen's death.
Responding to the allegations, Detective Inspector Bruce Scott said there was nothing further to add to the morning's media release.