Police have said the murders may be linked to the theft of two PlayStation Portable consoles, which they believe were taken on the night of the killings.
A laptop computer was also stolen from the flat six days before the attack.
A police spokesman said yesterday the suspect was white, between 30 and 40, slim and wearing a light coloured baseball cap and a dark top, blue jeans and white trainers.
The spokesman added: “We believe anyone involved in this scene would have been bloodstained when they left the area.
“Recently, Laurent told his mother he had bought two hand-held PlayStations. We have not been able to locate these and it is believed they were stolen.