A former FBI agent says the Annie McCarrick case should be upgraded to a murder investigation.
This week marks the 29th anniversary of the American woman's disappearance from her Dublin home.
Annie McCarrick is from Long Island in the US and she travelled here to study, living in Sandymount in Dublin with two friends.
On Friday, March 26th, 1993, the 27-year-old left her house to go walking in County Wicklow and vanished without trace.
Former FBI agent Kenneth Strange is a private investigator in California and family friend of the McCarricks.
“I think she was heading out to Enniskerry,” he said.
“Apparently there was a sighting on the bus going over to Enniskerry and then she vanished from the face of the Earth.”
Though she's one of seven women who disappeared in Leinster over a five-year period in the 1990s, it remains a missing person's case.
Mr Strange travelled here last September to retrace Annie's final steps as he investigates the case for her family.
“When someone vanishes and they are part of kind of a series of women that vanish and there is no evidence whatsoever and it is all in the same area, then I would say we are talking about murder.”
He believes Gardaí should upgrade the case to a murder investigation.
“If upgrading it means to throw more resources at it and more man-hours and give it much more thought, I would say yes, I would be very much for that,” he said.
“Certainly, that would be beneficial and I am for anything that would solve the case.”
Mr Strange said he remains positive there could be a breakthrough in the case.
“I’ve followed cases like this and even after many, many years, something can come up,” he said.
“Somebody recalls something, somebody reveals something or maybe a body is discovered in a field – some hunter’s dogs finds bones or something like that.
“So, I like to keep the faith. I hope something positive will come and I think it will.”
Gardaí say the investigation into the disappearance of Annie McCarrick remains open and active.