A senior official at Bahrain's Public Prosecutor's office said a Bahraini princess who works as a police officer is on trial for torturing two doctors.
Sheikha Noura bint Ibrahim Al Khalifa is also facing a separate trial for assaulting Aayat Al Qormozi, a young female Shiite opposition activist, while she was in detention during the same period, said Nawaf Hamza, head of the Public Prosecution's Special Investigation Unit.
"The charge is that she used torture, force and threats against the victims Zahra Al Sammak and Kholoud Al Durazi to make them confess to a crime," said Mr Hamza, referring to the two doctors.
According to Ms Al Sammak's lawyer, the alleged torture took place in March and April 2011, a period when the kingdom was convulsed by unrest led by majority Shiites demanding reform.
Fareed Ghazi, Sheikha Noura's lawyer, said his client did not wish to comment "but denies all charges against her".
An independent commission said 35 people died during the unrest, but the opposition puts that number at more than 80.
Sheikha Noura is about 29, according to media reports. At the time of the protests in 2011, she worked in the police drugs control unit, but has since moved to another department, according to Mr Ghazi.
Bahrain's information minister, Samira Rajab, confirmed Sheikha Noura was on trial in both cases.
"There was an investigation and her case was then referred to the court," she said.
Ms Rajab said Sheikha Noura's trial was part of the Bahraini government's accountability drive following the publication of the so-called "Bassiouni" report last year, which detailed the police's use of excessive force, including confessions under torture.
The Bahrain government says it has taken steps to address the brutality.
Since March 2011, at least 60 health professionals have been tried and sentenced to jail terms of up to 15 years on charges including attempting to bring down the government, according the rights group Physicians for Human Rights.
Most appealed and the majority had their sentences reduced or quashed, including Ms Al Sammak.
Ms Al Durazi was detained for allegedly providing false news about people injured in the unrest and inciting hatred of the government.
In the second case against Sheikha Noura, activist and poet Aayat Al Qormozi, born in 1991, says the princess applied electric shocks to her face, spat in her mouth and beat her while she was in detention, Al Qormozi's lawyer Reem Khalaf said. However, the charge against Sheikha Noura in this case makes no reference to torture.
Al Qormozi was jailed for a year in 2011 for insulting the king.
The lawyer added that the trial of Sheikha Noura on the charges relating to Al Qormozi began in June 2012. The next hearing would be on February 7, she said.
In the case concerning the two doctors, Sheikha Noura's lawyer said the princess's trial had started in October 2012 and that the next hearing was set for February 3.