Former Thai Prime Minister Yingluck Shinawatra (L) and her son Supasek Amornchat (R) gesture in a traditional greeting to the media as they arrive at Bangkok's Suvarnabhumi Airport July 23, 2014. [Photo/Agencies]

BANGKOK - Former Thai Prime Minister Yingluck Shinawatra has returned to Thailand from her vacation as scheduled, quashing speculation that she might flee the country to avoid a thorny case, local media reported Monday.

She returned to Thai capital Bangkok at about 10 p.m. local time on Sunday via a private jet from Singapore and left Don Mueang airport using a back door, Bangkok Post reported.

With permission from the junta, Yingluck left Thailand late July to vacation in Europe and the United States.

During her vacation, Yingluck reportedly attended the celebration for the 65th birthday of her brother Thaksin Shinawatra, a former premier who is now living in self-exile, in Paris.

Yingluck will have to fight a high-profile case in which the National Anti-Corruption Commission (NACC) has accused her of negligence of duty in overseeing a controversial rice-pledging scheme.

The NACC has forwarded the case to the Office of the Attorney- General (OAG) for indictment. The OAG is yet to examine the evidence and witnesses to decide if there are sufficient grounds for pressing charges against Yingluck in the Supreme Court's Criminal Division for Holders of Political Positions.

If found guilty, Yingluck could face a jail term as well as a five-year ban from politics.

In the meantime, an investigative panel of the Election Commission (EC) has reportedly alleged that the ousted premier, along with eight other former cabinet ministers and national police chief, had abused power by using public funds to campaign for the already-nullified February 2 general election.

All involved in the case will be called to defend themselves before the panel, pending further action.

The EC will have to decide whether to take the case to the Supreme Court's Election Cases Division for ruling. If found guilty, those involved could face up to 10 years in prison, a maximum fine of 200,000 baht (about $6,186 dollars) and a 10-year ban from elections.