News of the deaths spread to the family of Seattle resident Ryan Kells, whose fiancee was one of two women who died suddenly after staying in adjoining rooms in a hotel on Thailand's Phi Phi island in 2009.
Mr Kells said that almost two years after his partner Jill St Onge, 27, and Norwegian woman Julie Bergheim died, their deaths remained a mystery.
The 32-year-old said he felt sick on hearing of the Chiang Mai deaths, and could relate to the frustration the Carters felt at the handling of the investigation.
The couple had been engaged for 21 days and were nearing the end of three months of backpacking in Southeast Asia when Ms St Onge and Ms Bergheim died of heart and lung failure.
Mr Kells believes some sort of toxic gas killed the women because they both had respiratory problems.
"Those were Jill's last words, 'I can't breathe'."
Before autopsies were done on the women - who never met - Thai authorities had described their deaths as coincidental.
Mr Kells said he was quickly made to pay US$250 ($313) for a speedboat to escort Ms St Onge's body to the mainland.
"I didn't think at the time, but now it's pretty obvious, that they were just trying to get me away from the island."
The boat broke down halfway across the Andaman Sea in 1.5m waves.
"This whole time Jill's body was on the floor of the boat bouncing up and down. So I actually got on the floor with her and just held her head."
While Ms St Onge's death made local papers in the US and Thailand, "after a little while the story died and that was that".
He hoped the Carters' website might prevent such incidents being forgotten and pressure authorities to investigate them.
"To think that several families had to go through what Jill's family had to deal with. I would support any sort of action."
Mr Carter said the website would encourage people like Mr Kells to submit their own stories so their events weren't forgotten or ignored.
He is also considering writing to Thailand's Princess Bajrakitiyabha to ask for her help in investigating the Downtown Inn.
"She is a lawyer with a deep compassion for human rights.
"And as this situation is one not only of respecting human rights, but also of national significance involving a number of nations."