Hallowe'en horror took on a whole new meaning for revellers who consumed drugs at a house party in west Dublin and then began to fall into unconsciousness early last Sunday morning.

In total, 10 people attended hospital after consuming still unknown substances at three separate addresses at Annaly Court in Ongar, Dublin 15. Three men were originally described as being in a serious condition but have all since recovered and been released from Connolly hospital in Blanchardstown.

Initially it was believed that some party-goers had taken GHB, also known as liquid ecstasy. Despite its nickname, GHB has a sedative effect in stark contrast to the stimulant impact regular ecstasy has on users.

However, a senior garda involved in the investigation told the Sunday Tribune it was no longer certain that GHB had been consumed. Detectives are still awaiting results from the forensic state laboratory that will confirm the make-up of the drugs consumed. The results are expected early this week.

"It really could have been anything. It could well be one of the legal highs sold here or a combination of several drugs combined and then alcohol on top of that. There does seem to be some kind of a sedative derivative in whatever they took because people fell unconscious," said the source.

Liquid ecstasy, which comes in powder as well as liquid form, is quite rare in Ireland. However, drugs-squad gardaí are increasingly coming across drugs that they have never seen before because of the proliferation of 'legal highs' and drugs now available to buy online.

Full swing

The scene that unfolded in Ongar last Saturday night was one that was being replicated all over the country, as Hallowe'en parties got into full swing.

Young couple Ian Byrne and Mary O'Leary decided to throw a party at their home in Annaly Court. Some of their friends lived on the same street, so it was decided that the party would be spread across three houses. About 30 guests attended altogether.

All seemed to be going well until about 3am when a man in his 20s collapsed. Dublin Fire Brigade was called, and it was initially suspected that the man was suffering from carbon monoxide poisoning. After taking him to hospital, the emergency services returned to the scene and found a number of other people seriously ill. They were taken to the hospital by ambulance and the paramedics were told by party-goers that drugs had been consumed.

Gardaí were immediately called and the Garda National Drugs Unit (GNDU), technical bureau and Blanchardstown detectives arrived at the scene. What was of paramount importance was not arresting those in possession of drugs but getting everyone who had taken something to the hospital.

"That was the most important thing," said a separate garda source. "We didn't want the nightmare scenario of someone's son or daughter who'd left the party and gone home to bed lying in a coma while their parents were downstairs preparing Sunday lunch. It was most important to get the message out there that anyone who went to the party and took drugs needed to get themselves to hospital. We did get the message out there effectively and, thankfully, no one lost their life because of it."

Questioned

The three houses were searched by gardaí overnight. Small amounts of drugs were recovered at the scene and sent for analysis. On Sunday, the technical bureau also continued its work at the three houses. About 20 people, including Byrne and O'Leary, have been questioned.

No one has been arrested but detectives are understood to be anxious to bring charges against those believed to be responsible for supplying drugs to the party.

"It's likely more than one drug was consumed. The investigation is at an early stage but it is a very wide investigation," said the source.

No one who's so far been interviewed – including those who were admitted to hospital – has 'given up' the person or people they bought the drugs from. But it was the actions of the young couple who threw the party in the aftermath of the event that has kept this story in the headlines.

The parents of two young children boasted about their exploits on the social-networking site Bebo – not a wise move, as gardaí are now examining the information the couple decided to share with the world online, including photos of people taking drugs.

The bill the taxpayer has footed for emergency services, hospital admissions and dozens of specialist gardaí to deal with the near-tragedy has so far cost in the region of €20,000. And that figure is likely to rise as the extensive garda investigation continues. Despite all this – and the fact the couple told journalists last Sunday that the drugs at their party must have been "smuggled in" – they then proceeded to boast about their party lifestyle online on Monday.

Byrne cheekily wrote on Bebo: "At least I knocked John and Edward off the headlines." He also decided to share with the world that he is "happiest when smoking hash" or playing with his children.

His girlfriend O'Leary's Bebo page is even worse. A photo of a young woman with several lines of a white powder was visible for all to see until she set her online profile to 'private' on Monday evening. The photograph appears to have been taken at the couple's home but gardaí do not believe it was taken on the night of the party.

O'Leary complains on her Bebo page: "Cant belive d papers have me and ians photos and names on it and written a load of b*******!! She added: "Der was other gafs aswel and der just putting it aL on my gaf."

Byrne has also posted a photo of himself with a large joint drawn into the picture.

"Well, it really wasn't the smartest thing for them to do, posting all that stuff on Bebo," said a garda source. "They'll live to regret it no doubt. We are of course looking at everything said and photos they put up on online."

'Recreational'

On Tuesday, Byrne's father also got himself involved in the story by publicly defending his son. "He does smoke hash like a lot of people do but he is not openly taking ecstasy or a cocktail of drugs. He uses it as a recreational drug," Harry Byrne said.

He also described his son as a "loving father" who would not expose his children to a drug environment. The couple's two children were staying with their grandparents on Hallowe'en night and there is no suggestion at this stage that social services may take their children away.

Four days after the drug-fuelled party, gardaí at Blanchardstown – who are also probing the events at the house party in Ongar – seized €1m worth of cocaine at a house in Blakestown. "It was unrelated to the incident at the party but there has been a huge number of drug seizures in recent months," added the source. There is a huge appetite for illegal drugs in this country. That party just shows how badly wrong things can go."