The parents of Jesse Galganov sombrely marked his 23rd birthday with no idea where they son may be.

"Today is Jesse's birthday. He's 23 years old. He's just, to me, a kid," said his father Todd Galganov.

Jesse disappeared at the end of September but was only declared missing in mid-October when he failed to make a rendezvous after hiking the Santa Cruz trail.

His parents flew to Peru to get involved in search efforts and have also raised money.

So far more than one million dollars has been spent on the search.

"I don't know if he underestimated the climate, or underestimated the people. God knows what happened to him. You know I still have hope. Until I know that something terrible has happened to him I still have hope still believe he's alive and out there. We have to find him," said Galganov.

Investigators have scoured the mountain that is Jesse's last known location.

Jesse's mother, Alisa Clamen, said they are now looking for four Americans who may have been the last to see Jesse on the trail.

"The more people that know about it the more people will say 'hey I think you were there at that time.' If you have some pictures, or if you know someone who was in that area or hiking in the Santa Cruz track... There's no way of knowing who saw him and the only way is to do this is meticulously going through and just figuring out how to contact anyone who was there," said Clamen.

News of Galganov’s disappearance spread across social media last year through targeted PR campaigns using Facebook and Instagram ads.

The family also launched online crowdfunding campaigns to help bolster search efforts.

A GoFundMe page has accrued over $180,000 in donations at time of writing, and a similar campaign on CanadaHelps.org has also helped, said Clamen.

Todd will spend Friday putting up more posters in Huaraz, Peru.

He said he has been overwhelmed by the support from family, friends, and strangers.

"He's out there somewhere. Let's find him and bring him home. I can't keep going all my life, and my son is never found," said Todd.

Anyone with information is asked to email helpusfindjesse@gmail.com.