New Delhi (CNN) -- A lawyer who says he's representing three of the five men charged with raping and fatally beating a woman on a New Delhi bus said Tuesday that he has advised his clients to plead not guilty. 

"So far they have agreed to my advice, but a clearer picture will emerge by tomorrow evening," the attorney, Manohar Lal Sharma, told CNN. "I fear they might come under pressure to change their mind." 

Sharma said one of those he is representing is Ram Singh, the main accused in the case. The other two are Mukesh Singh and Akshay Thakur, he said. 

The horrific attack on the 23-year-old woman in New Delhi on December 16 has prompted angry protests over the country's treatment of women and handling of sexual attacks. India's interior minister has said he was also working with security officials to strengthen laws regarding rape and assault following the attack, which also stirred outrage worldwide. 

Proceedings against the five adult suspects began Monday, when a New Delhi judge ordered the trial closed after tempers flared inside the packed courtroom. Some lawyers loudly criticized colleagues for offering to represent the suspects, with one young lawyer shouting at Sharma, "You will not defend those barbarians." 

The magistrate, Namrita Aggarwal, ordered that the hearing take place behind closed doors and barred news outlets from publishing proceedings related to the case without the court's permission, citing concerns about the suspects' safety. 

The five men in court this week are charged with murder, rape and kidnapping, and could be sentenced to death if convicted. A juvenile court will take up the matter of determining the age of a sixth suspect, who claims to be 17 and therefore not old enough to be tried as an adult, CNN affiliate IBN reported. 
where was the woman fatally beaten?
fatally beating a woman on a New Delhi bus