Kamal Nath was sworn in as chief minister of Madhya Pradesh today in the shadow of protests over his alleged role in the 1984 anti-Sikh riots, for which his Congress colleague Sajjan Kumar was convicted. Former Congress MP Sajjan Kumar, 73, was sentenced to jail for life by the Delhi High Court, which cancelled his acquittal by a trial court and said he did play a part in the mob killings of Sikhs after the assassination of then prime minister Indira Gandhi by her Sikh bodyguards on October 31, 1984.