Gardaí investigating the suspected murder of a young Roma teenager are preparing to travel to Romania to interview her brother, to whom she made a frantic phone call just hours before she was shot dead.

Detectives believe that 19-year-old Mariora Rostas was abducted, raped and murdered within 24 hours of vanishing last January.

After willingly getting into a car with a Dublin criminal who is well known to gardaí, the teenager was taken to a house in Dublin's south inner city where she was raped and held captive.

But against all odds, she managed to telephone her brother in Romania and tried to tell him where she was. "She told her brother she was being held against her will and had been violated by men. She could see a street sign from the house and spelt out the letters 'B R U and I D' before she was cut off," a senior garda involved in the investigation said.

"We believe she was in a house on Brabazon Street and she was trying to spell Brabazon Sraid, but she could barely read or write."

Gardaí last week arrested four people in relation to her disappearance. They believe a 29-year-old man shot her dead and members of his family assisted in the subsequent cover-up. All have since been released without charge but gardaí say the investigation is continuing and the search for her body has been given priority. "Our information is that one man had sex with her and then shot her several times afterwards. His nickname isn't 'Madman' for nothing."

The Roma teenager was in Ireland for only three weeks before she disappeared. Her parents, Marioara and Dumitru, sent for her to come to Ireland for a holiday and to recuperate after being viciously assaulted at her home in Timisoara in Romania. Her leg was broken in the attack. "She was brought to Ireland 'for a rest'," her father told gardaí. At home, her job was to mind all her younger siblings while her parents and brother, Dumitru jnr, spent their days begging in Dublin city centre. Nearly all of the money they raised was sent home to Romania and when Marioara arrived here, she too was sent out begging by her father.

Some of Marioara's aunts and uncles were part of the group that were last year living at the Ballymun intersection of the M50 roundabout. Before her disappearance, the teenager and her family were squatting at a house in Donabate, with no running water or sanitation.

On 6 January, Marioara headed off with her 16-year-old brother to beg on East Lombard Street, at the junction of Pearse Street. "Begging is a way of life for them. She didn't wear the traditional gypsy clothes, she was wearing jeans and a T-shirt and was a pretty girl. Maybe that's why the car stopped. We don't know why she got into it," the garda added.

Assist

Dumitru jnr was handed €10 and was told by the driver to go get himself a burger. He was later able to assist gardaí in identifying the 2001 Ford Mondeo with a Louth registration, which had belonged to the chief suspect at the time and is being forensically examined. Yards from where Marioara disappeared, members of her extended family continue to beg.

The Sunday Tribune spoke briefly to one of her relations, also named Marioara Rostas, who was begging outside Pearse Street Dart station last week. She could only confirm in broken English that she was related to the missing teenager. "The family are, of course, devastated. Her father went into the Bridewell garda station a couple of days after she went missing. He's told us Marioara was a good girl, a quiet girl. They are very surprised she got into the car," the garda added.

"Her younger brother is very upset too, because he was the last one to see and he left her alone. Unfortunately, her mother is in complete denial that she's dead even though we've explained our reasons to believe she was murdered."

Blood

Gardaí have found traces of blood at the house where it is believed she was killed. The chief suspect set fire to the premises shortly after she disappeared, in an attempt to destroy forensic evidence. But advances in forensics ensured gardaí were able to uncover a miniscule blood sample from the fire-damaged house, which they hope will match Marioara's DNA. Sources say they have firm suspicions that the house on Brabazon Street was operating as a brothel, at least some of the time. A cousin of the chief suspect is believed to have been working as a prostitute out of the house and another young woman overdosed and died a few months prior to that.

"Neighbours reported seeing a young, dark-haired girl going into the house, that may well have been Marioara. She seemed to go in willingly. But we believe she was killed within 24 hours of going into that house."

Gardaí are working on the theory that Marioara was raped by the chief suspect but have no other reason to believe she had sex with other men, aside from her comments to her brother on the telephone.

Two anonymous tip-offs have assisted the investigation. In June, an Irishman phoned gardaí and supplied information about the murder and cover-up. He claimed to have overheard a conversation about it between two men in a pub, an explanation discounted by gardaí.

Three months later, a woman phoned gardaí and provided the authorities with more information in relation to the case, which has led them to search the Grand Canal for the gun they believe was used in the murder.

Sources say a number of lines of enquiry are being pursued as to the whereabouts of Mariora's body but it has been ruled out that she was dumped at the Grand Canal.

While Marioara's parents have been arrested for begging, they are not considered criminals by the gardaí and are not involved with any Romanian gangs operating here. Highly organised Roma begging gangs throughout Europe make considerable amount sums of money, which is all sent home to Romania where expensive cars and houses are bought for extended family members, items seen as status symbols to the Roma community.

Beggars

"But Marioara's family would be on the bottom rung of Roma gypsies really. They're beggars, not criminals. Her father was initially a horse trader. They are dirt poor, the family have left Donabate and are now squatting on Richmond Road somewhere, although they tend to move around a lot. They'll go back home to Romania for Christmas but will come back after that, this is where they make all their money. They want to come back to see how our investigation is going."

Detectives have plenty of experience investigating the disappearance of Roma teenagers and girls in Ireland. Arranged marriages at a young age are the norm in the Roma community. In their culture, husbands must pay a dowry to the woman's family in return for her hand in marriage. There have been instances in Ireland where Roma teenagers and girls are abducted by other Romanians and raped, sometimes by several men. The women are then returned to their families but no man will pay the full dowry price as she is "no longer pure".

Often, one of the men who have raped the girl then offers to marry her but pays a reduced dowry price to her family because she's no longer a virgin. Initially, gardaí believed Marioara had been abducted by Romanians but as the weeks turned into months, it soon emerged this case was different. Gardaí raided 26 brothels run by Romanian gangs in Wexford, the UK and Belgium. "We were stumped because we kept coming up with nothing until we got the first anonymous phone call. Then everything started falling into place. We took this case very seriously from the beginning – we're talking about an 18-year-old who was picked up off the street and later murdered."

The investigation is now focused on finding the young woman's remains.

"That's an absolute priority. This investigation will not be dropped by the gardaí. No one shouted for Marioana all her life. The papers hardly covered her disappearance until we announced last week we were sure she was murdered.

"That wouldn't be the case if it was an Irish 18-year-old who was raped and murdered from Dublin 4."