The search for missing 17-year-old "Nong Namtan" has ended in a tragedy with her family on Saturday confirming the girl's death.

Namtan, or Napassorn, from Udon Thani, was seen leaving her apartment in Pathum Thani's Rangsit area on May 1. Her family lost contact with her around midnight. 

Police said Namtan called a taxi via an application to drop her off at Rama III Road where she hailed another taxi to Pattaya's Walking Street.

She returned to the Rama III area with the second taxi before disappearing.

A Facebook user named Papassorn, believed to be her relative, on Saturday wrote that Namtan was gone and thanked those who helped looked for her.

Namtan, the poster said, had jumped into Chao Phraya River and her body was found on May 3. However, the family had several questions surrounding Namtan's death and wanted truth and justice for the teenager.

The story surrounding Namtan's last day alive remains full of unanswered questions.

Namtan had made several phone calls before switching off her phone on the first day of her disappearance, and it was unlikely she had bought a new SIM card as she had no ID card with her at that time.

The girl had travelled to Pattaya, but stayed only briefly and returned to Bangkok. She was caught by security cameras walking by herself on Rama III Road but there was no footage beyond that point.

The family had also contacted the bank for information about Namtan's transactions but was still waiting for an answer.