Seven members of SEBI's probe team spent five hours grilling Satyam's founder Ramalinga Raju and its former MD Rama Raju for the second day on Thursday.
The two brothers were interrogated separately by SEBI officials, who split into two teams. Two more officials joined the existing five-member team today.
The Supreme Court had earlier this week granted the regulator permission to question the Raju brothers inside the jail, where they are awaiting charges to be filed in the case relating to the accounting fraud in Satyam Computer.
Although the SEBI investigating team, headed by Sunil Kumar, was tight-lipped about the probe, it is learnt that the probe focussed on 'buying, selling and dealing' in Satyam shares by the Raju brothers.
"They (SEBI team) came at 0930 hrs. After forming two teams, they began separate interrogation of Raju brothers from 1000 hrs, which continued till 1700 hrs with a break for lunch," a jail official said.
Meanwhile, the Serious Fraud Investigation Office has sought court permission to interrogate the two brothers in connection with the Rs 7,800 crore fraud in Satyam.