A 52-year-old family friend accused of taking a 14-year-old runaway Bangkok schoolgirl to Chiang Mai has confessed that he had sex with her last year, police say.

Ronnachit Bamrungjit, of Bangkok, appeared on Saturday in the Southern Bangkok Criminal Court, which ordered him detained for the next 12 days pending further investigations in the case that has shocked the country.

Mr Ronnachit, who is married, was caught with the girl on Thursday night in a Chiang Mai hotel and taken to Bangkok to face charges.

The girl is now under the care of officials from the Chiang Mai branch of the Social Development and Human Security Ministry. She was examined by doctors on Friday for signs of possible abuse, which would determine the course of legal action against the suspect.

A Mathayom Suksa 2 student at a Bangkok school, the girl failed to come home after taking a midterm exam on Dec 27 and her parents could not reach her. They alerted police officers at the Phlap Plachai 1 station and later sought help from the Crime Suppression Division.

Police investigators focused their attention on Mr Ronnachit after learning that he was close to the family of the girl. He also tutored the girl, who called him uncle. Mobile phone records led them to Chiang Mai.

They later discovered that the pair had travelled on the suspect’s motorbike from Bangkok to the northern province, stopping at some attractions along the route. They reportedly arrived in Chiang Mai on Tuesday.

A cash withdrawal from a bank in Chiang Mai on Wednesday provided a further clue, as did CCTV footage that showed the suspect and the girl walking at a department store in Chiang Mai. Officers then sought court approval to arrest Mr Ronnachit and found him in a local hotel around 8.30pm on Thursday.

During the interrogation, police said, the suspect confessed that last June he had taken the girl to a department store in Bangkok where he gave her a tutoring lesson. Afterward, he had sex with her inside his car before driving her home.

Mr Ronnachit was charged with depriving a minor aged below 15 for obscene purposes, depriving her of parental care for obscene purposes, and having sex with a girl aged below 15 who was not his wife, regardless of whether the girl consented. The suspect confessed to all charges, police said.