Himachal Pradesh Chief Minister Virbhadra Singh reached the Central Bureau of Investigation (CBI) headquarters on Friday for the second round of questioning in the case involving acquiring wealth disproportionate to his known sources of income.The questioning started a few minutes after the 81-year-old senior Congress leader arrived at the CBI office around 10.50 a.m., sources said.Singh, who arrived in Delhi on Wednesday, was on Thursday questioned for around five hours and confronted with various "evidence" of over Rs 6.03 crore worth of unaccounted assets.A case was registered on September 23 last year under the Prevention of Corruption Act against Singh, his wife Pratibha Singh, Life Insurance Corporation agent Anand Chauhan and associate Chunni Lal.A preliminary inquiry allegedly found that Virbhadra Singh accumulated assets worth Rs 6.03 crore in his and his family members' names which were disproportionate to his known sources of income.