Satellite images show a special train possibly belonging to North Korean leader Kim Jong Un parked in one of the country's resort towns last week.
The pictures were reviewed by Washington-based project 38 North, which monitors North Korean affairs.
That came amid conflicting reports as to Kim's whereabouts as speculation simmers over his health.
38 North says that the train was parked at the quote "leadership station" in the city of Wonsan on April 21 and 23, which is reportedly reserved for the Kim family's use.
Reuters has not been able to independently verify if the train belonged to Kim, or if he himself was in Wonsan.
But it backs up remarks from top officials in South Korea on Sunday (April 26).
Top foreign policy advisor Moon Chung-in said Kim is alive and well, and has stayed in Wonsan for weeks.
Speculation about Kim's health first arose after his absence from one of the country's biggest yearly events -- the birthday of his grandfather Kim Il-Sung earlier this month.
Since then he's remained out of sight.
Then last week Seoul-based website Daily NK reported a source telling them Kim was recovering from a cardiovascular procedure.
Since then, multiple South Korean media reports have cited unnamed sources that point to Kim staying in the Wonsan area.
And on Friday (April 24) a South Korean source told Reuters their intelligence was that Kim was alive and would make an appearance soon.
Reuters has also reported that China dispatched a team of medical experts to North Korea last week, according to three people familiar with the situation.
However, its not immediately clear what that trip may signal in terms of Kim's health.
Reporting on North Korea is notoriously difficult due to tight information control and experts caution that Kim has disappeared from his country's state media before.
They last reported Kim's whereabouts when he presided over a meeting on April 11.
Kim vanished for over a month in 2014 and North Korean state TV later showed him walking with a limp.