Dutch and Irish police were last night still trying to trace a man and woman whose passports were found in the apartment outside The Hague where three Irish men were found mutilated and murdered.
The five passports found in the apartment belong to two brothers, aged 29 and 22, from Bansha, Co Tipperary; a 27-year-old Northern Ireland woman; and two other men in their late 20s from Ennis, Co Clare, and Kilfinnan, Co Limerick.
Gardai yesterday informed the families of the four men of the discovery of the passports and said tests were continuing on the bodies to verify their identities. It is expected that positive results will be available this morning.
The RUC said last night that it was investigating "a possible Northern Ireland connect in relation to one passport" but had no further information. The Northern Ireland woman has a British passport.
According to Dutch police sources yesterday, it appears the young Irish people living in the apartment had been involved in the manufacture of amphetamine sulphate, the drug known as "speed".
It is believed they may also have had contact with eastern European criminals who control the supply of the chemicals used in the manufacture of the drug. These criminal gangs have a reputation for extreme violence in the Netherlands.
According to police sources yesterday there was no clear motive for the murders. But it is suspected the Irish men either reneged on a payment for chemicals or were blamed for the seizure of drugs or chemicals by police.
They were attacked in their apartment at Gevers Deynootweg, in the seaside resort of Scheveningen, just outside The Hague, early on Saturday morning.
According to local reports they were subjected to considerable violence, and their bodies showed signs of mutilation.
Police said they could not confirm a report that one of the corpses contained traces of builder's cavity filler, a material sprayed from a tube to fill gaps in walls and window frames.
It is believed that the three were herded or dragged into the bathroom and their killers then poured flammable liquid over them and set them on fire. The fire spread to the rest of the apartment, causing the evacuation of the block.
At first Dutch police were unable to ascertain the identities of the bodies but made one tentative identification on Tuesday. It was still believed at that stage that two of the dead were possibly Dutch nationals.
However, yesterday further tests indicated that all three were Irish. Final tests on dental records and fingerprints were being completed yesterday. There was considerable concern about the missing man and woman yesterday.
The murders are being reported in the Dutch media as part of an increasingly violent trend in drug-related crime. According to police sources, violence has been increasing as gangs try to intimidate each other.
The worst violence is said to emanate from eastern Europeans who are involved in the manufacture of chemicals used to make synthetic drugs such as amphetamine, ecstasy and LSD.