Police revealed someone broke into Mei Fen's home a month after her killing and left a bizarre note containing a biblical verse.
Detective Senior Sergeant van den Heuvel says it may have been the murderer returning to the scene of the crime.
"If it is the killer, then it's a rather paradoxical thing to do I think. To have slain a young woman, a mother of two, and then to come back and leave such a religious note.
He says the intruder left the card some time after the scene examination was complete.
"We can't discount that it is the killer returning back to the scene, to leave this card behind. And if that is the case, it's a rather unusual thing to do."