Despite intensive searches and years of investigations by gardaí, her fate has never been discovered.
While the loss has been hugely distressing for her family in America, a sense of unfinished business is also still felt keenly by former Garda Assistant Commissioner Martin Donnellan, the man who led the investigation into her disappearance.
Speaking publicly at length for the first time yesterday about this cold case, Mr Donnellan said he believes that Annie was the victim of a serial killer responsible for a spate of murders of young women in Leinster between 1993 and 1998.
“Girls started to disappear in this country around that time,” he told John Murray on RTÉ radio.
“There was Deirdre Jacob, only 18, who disappeared in July of 1998. She had gone to the post office in Newbridge and we had CCTV footage of her there. She walked home in broad daylight, was seen in various places, and then just disappeared. It was obvious that she had been snatched off the street.
“Then there was Jo-Jo Dullard, who went missing in 1995, also in mysterious circumstances. Added to that is the disappearance of Ciara Breen in Dundalk, Fiona Pender in Tullamore, and Fiona Sinnot in Wexford.”
Mr Donnellan believes that at least three of these cases are connected. “All three were on their own when they disappeared,” he said. “There was never a trace of clothes found, which is unusual. In each case, the clothing the girls were wearing was very distinctive but we never came across a single item. They were each probably bundled into a car or van.”
In all, seven women vanished without trace. The last to disappear was in 1998 which, according to Mr Donnellan, indicates that there may be one person responsible for at least some of them.
“It means that he [the culprit] must have been in jail or had left the country after that,” said Mr Donnellan.
Annie, from Long Island in New York, had gone to college in Ireland and returned here to trace her family’s heritage.
She shared an apartment with two girls in Sandymount on Dublin’s southside and was looking forward to a visit from her mother, Nancy. On Friday, Mar 26, 1993, just days before her mother was due to arrive, Annie failed to show up at her workplace as expected to pick up her wages.
On Saturday, when her friends arrived at her apartment for a previously arranged dinner party, there was no sign of her.
Annie’s father, John, who has since died, said he knew immediately something was terribly wrong when her friends in Dublin called him to say they didn’t know where Annie was.
“She was always reaching out and touching someone... She would never have gone a day without talking to someone… We were very, very concerned,” he told ABC News in America.
Mr Donnellan recalls the early days of the investigation: “I was off at the weekend on that Friday and Saturday, and I got a call from Irishtown station that a girl had disappeared in very mysterious circumstances.
“She was staying in a flat near Sandymount with two other girls. They were going to their homes in Cork so she was at a loose end and phoned a friend to go for a walk in Enniskerry, but her friend couldn’t go so she went off alone.”
The mystery deepens with various sightings of Annie after that. She was captured on CCTV footage in the AIB in Sandymount and later at the local supermarket.
She then got the bus to Ranelagh, where she hopped on another bus to Enniskerry.
The final confirmed sighting of Annie was by a colleague who worked with her, in a restaurant in Donnybrook. One person came forward to say they thought they had served her in the post office in Enniskerry, although this was never confirmed.
Another unconfirmed sighting was in Johnnie Fox’s pub, a traditional music venue in the Dublin mountains. Doorman Sam Doran came forward after his colleague, Paul O’Reilly, pointed out Annie’s picture in the newspapers. Doran described Annie as having come to the door of the “Hooley Room” without realising there was a cover charge.
He said she was accompanied by a man wearing a wax jacket. He paid for her and was reportedly paying for her throughout the evening. Annie was never seen leaving the pub, and the man she was with has never come forward.
One of the prime suspects in at least three of these cases is convicted rapist Larry Murphy. From Baltinglass, Co Wicklow, he was jailed for 15 years for the abduction, rape, and attempted murder of a woman in Feb 2000. He was released in 2010 and is now believed to be living in the Netherlands.
Annie’s disappearance still perplexes Mr Donnellan: “We had always hoped that we would get the right call. It is so tragic. If people went missing in the US, you would not be surprised, but not in the island of saints and scholars.”
1. Annie McCarrick, 26. Disappeared on March 26, 1993. An American living in Sandymount, she was reportedly last seen in Johnnie Fox’s Pub in Glencullen, Co Dublin.
2. Eva Brennan, 39. She disappeared after leaving a family lunch at her parents’ house in Rathdown Park, Rathgar, Dublin, on July 25, 1993.
3. Josephine (Jo-Jo) Dullard, 21. She disappeared on Nov 9, 1995. She vanished while hitch-hiking home from Dublin to Kilkenny. A witness saw her using a pay phone but she was never seen again.
4. Fiona Pender, 25. Fiona disappeared from her home at Church St , Tullamore, Co Offaly on Aug 22, 1996. She was seven months pregnant and had spent the previous day shopping for baby clothes with her mother.
5. Ciara Breen, 18. Ciara went missing from her home in Bachelor’s Walk, Dundalk, on Feb 13, 1997. It is thought that she had a pre-arranged meeting with someone unknown, but this has not been confirmed.
6. Deirdre Jacob, 18. She vanished just yards from her parents’ home in 1998. Passing motorists saw her within yards of her parents’ drive-way, but for some unknown reason, she never made it there.
7. Fiona Sinnott, 19. Fiona, from Bridgetown, Co Wexford, went missing on the night of Feb 9, 1998 after a night out in Butler’s pub in Broadway.