Forensic scientists are examining the scene
Two men, believed to be from Lithuania, were already being questioned by police in Newry.
The two murdered men suffered brutal and violent deaths and had multiple injuries, according to detectives.
One of the victims, found dumped on a roadside near Warrenpoint on Wednesday has been positively identified as Lithuanian.
It is believed the other victim was also from Lithuania.
A house in Sandy Street in the town was sealed off before a forensic examination took place.
Police also carrid out searches in the Mayobridge area of County Down.
Billy Simmerton, an Honorary Consul for Lithuania, described the news as "shocking".
"I was in touch with the embassy this morning and it has come as a great shock and a great surprise to them," he said.
"They had been in touch with the PSNI and with the detective superintendent who is handling this case. They are just waiting for more information."
Forensic scientists are continuing their search of the murder scene on the Mound Road on Friday.
Officers are waiting for the results of post mortem examinations on the men, whose bodies were discovered on Mound Road, about a mile and a half from the town.
A murder investigation was launched following the discovery of the bodies.
A security operation was mounted after a man out walking discovered one of the bodies on the Mound Road, a mile and half from the town.
The second body was found after a close examination by the security forces.
Police in the Republic of Ireland, the Garda Siochana, and Interpol are helping police with the investigation.
Crew records on ships docked at Warrenpoint were also checked.
The men's bodies were moved from the scene on Thursday afternoon.