Commissioner Pat Byrne said yesterday he had set up a special team of detectives in an attempt to shed light on the disappearances. Psychological profiles of possible abductors are being prepared.
The moves came as intensive searches began in counties Carlow and Kildare for two men who tried to pull a 24-year-old woman into a red car at Tullow, Kildare, on Tuesday.
Judith Gahan, who has three children, was stalked by the car, and one man offered her a lift. When she declined he got out and grabbed her. Her clothes were torn but she escaped.
Existing inquiries are being overseen by the assistant commissioner in overall charge of the police's eastern region, Tony Hickey, who in 1996 headed investigations into the murder of journalist Veronica Guerin.
"We have no evidence unfortunately that [the eight women] are alive," Commissioner Byrne said. "We must assume as police investigators that they are dead. We have no bodies and no crime scene, which makes it extraordinarily difficult."
The serial killer theory was examined by chief superintendents at a special meeting during their six-monthly conference on Thursday and yesterday at the police force's training college in Templemore, County Tipperary.
Suspicions of links between the cases is fuelled by their proximity. Six of the eight women vanished within a 30-mile radius of Newbridge, Kildare. All but two occurred within 50 miles of the capital.
Detectives from earlier cases are now helping investigations into the disappearance of Deirdre Jacoban, an 18-year-old trainee teacher from County Kildare, last seen on 28 July.
Ms Jacob vanished after walking the mile from her home into Newbridge to post a money order. A man has confirmed giving a lift to a woman answering her description on the day she went missing, from nearby Clane to Carrickmacross, Monaghan, where she said she had friends.
The other women whose disappearances are being investigated are:
Ciara Breen, 18, of Bachelor's Walk, Dundalk, missing since 12 February.
Fiona Sinnott, 19, from Bridgetown, Wexford, who has a year-old daughter. She has not been seen since leaving a pub at Broadway, County Wexford, on 8 February. A restaurant worker, she was living at Ballycushlane after splitting with her boyfriend. In June police drained the nearby Lady's Island lake but found nothing.
Fiona Pender, 25, a former model and motorcycle enthusiast, disappeared from the flat she shared with her boyfriend in Tullamore, County Offaly, on 23 August 1996. She was seven months pregnant.
Jo Jo Dullard, 21, disappeared after trying to hitch a lift to her home at Callan, County Kilkenny, on 9 November 1995. She was last heard from when she called home from a rural phone box at Moone, Kildare.
Annie McCarrick, 26, an American student and qualified teacher working in a fashionable coffee shop and living in Sandymount, south Dublin, vanished after visiting a pub at Glencullen in the Dublin mountains on 26 March 1993, with a man in his twenties. A police image was issued but no one was charged.
The location has a macabre reputation; since 1979 several murder victims have been found buried in the Dublin and Wicklow mountains. In May 1993 Ms McCarrick's father, John McCarrick, from New York, offered a large reward for information. He said last week he accepted that his only daughter must be dead. Despite mountain searches by hundreds of volunteers, no body has been found.
There are also fears for Eva Brennan, missing from her Dublin home since 25 July 1993, and Catherine Madigan, also from Dublin. She has not seen been since 15 May this year.
Geography is arguably the biggest problem the police face. Resources have long been focused on border anti-terrorist work and Dublin drug-related crime, and the 11,000-strong force's ability to mount sustained large- scale inquiries in rural areas is limited, even with helicopter assistance.
The number of unresolved missing persons cases is already becoming a political controversy in a country where the sharp rise in crime since the early 1980s has made law and order an election battleground.
Last week the Fine Gael opposition reminded the justice minister, John O'Donoghue, of his commitment, before coming to power, to set up a missing persons unit. Fine Gael said that more than 80 people have disappeared since 1991, and insisted that the existing policy of handling cases separately under local superintendents was inadequate.Reuse content