Soithip Trisuddhi, permanent secretary for transport, said she had received a report that said Wanchai Saengkhao had been recruited due to cronyism. He was hired even though he had shown a report on his criminal record to the State Railway of Thailand (SRT), but the document was never verified.
The girl was raped and killed on the overnight southern train on its way from Surat Thani province to Bangkok from Saturday evening to Sunday morning.
Mrs Soithip said Mr Wanchai, 22, was among 90 employees that the SRT had recruited in one employment drive.
"This is a lesson for the SRT and clearly shows a total failure. It is right for society to blame it. This may prompt all SRT staff to love the SRT more and work efficiently to restore confidence in the organisation," Mrs Soithip said.
She acknowledged demands for the SRT governor to resign. She said the issue concerned the spirit of the executives. She urged the SRT board to convene an urgent meeting to consider a layoff option in the employment contract of the SRT governor.
Mrs Soithip said someone had to be held responsible for the matter as safety was at the heart of public services.
SRT governor Prapat Chongsanguan said on Wednesday he would not resign because that would not help solve the problem and he would have to compensate the SRT, but he would be ready to accept a dismissal order from the SRT board and he would not file a lawsuit.
Mr Prapat said Mr Wanchai had close connections with an executive of a major train station responsible for the recruitment drive and some action might have been taken to conceal his criminal record. It was earlier reported that Mr Wanchai had been prosecuted on narcotics charges.
The SRT governor said Mr Wanchai had been among 90 staff recruited on June 16.
Prasit Jindasri, chief of the SRT's Passenger Division, admitted on Wednesday that he had authority to approve the recruitment of the 90 staff working on sleeper carriages, including Mr Wanchai, and police had yet to send the criminal record of the man to the SRT.
Mr Prasit said Mr Wanchai had worked for the SRT as a monthly contracted employee since February. He denied he knew the suspected murderer personally.