The 27-year-old was last seen on June 8 as he was hiking in Grand Teton National Park in Wyoming.
Despite a week-long aerial and ground search, with up to 70 park staff involved in search operations each day, the US Park Service announced it was scaling back the search.
However, a Wyoming resident has since come forward after returning from an overseas trip to say they saw Mr McLaughlin in the late or early afternoon of June 8 which is later than the previous last known sightings on the same day.
The individual contacted authorities to reveal he had a conversation with Mr McLaughlin on the south side of the Bradley/Taggart moraine in Grand Teton National Park.
As a result, fresh searches were carried out.
Grand Teton National Park officials said: "The individual reported McLaughlin was headed south towards Taggart Lake and had a conversation with McLaughlin where he described where he worked, that he’s from Ireland, and currently living in Jackson.
"The reporting party continued hiking towards Bradley Lake and did not see McLaughlin again that evening."
Officials say "no evidence or clues" about the Irishman's whereabouts were found during the latest search but they are now asking members of the public in Wyoming to come forward with any information about Cian's disappearance.
Mr McLaughlin had been living and working in Jackson, Wyoming, near the Grand Teton National Park.
The search was initiated after the Dublin native failed to turn up for work in Jackson Hole, where he had been working as a snowboard instructor.
He is described as a solo hiker with shoulder-length hair and wearing round glasses. He was wearing a white shirt, shorts and a hat.
Intensive searches of the Garnet Canyon area where Mr McLaughlin was last seen took place last week involving helicopter searches and search-and-rescue dog teams.
More than 60 staff conducted ground search efforts on Thursday with teams flown into the Garnet Canyon area by the Teton Interagency Helicopter, while five search-and-rescue dog teams also took part in the operation.
However, the National Park Service announced last Friday that it was scaling back search efforts.
The Garnet Canyon trail is located near the picturesque Bradley Lake in the national park, a popular destination for visitors and hikers.
The trail on which it is believed that the missing man was last spotted is described by the National Park Service as a “strenuous” 13.5km round trip.
The National Park Service Investigative Services Branch have repeated calls for anyone with information to contact them.