The postmortem report, which is likely to be submitted before the Delhi high court on Monday, says that 19-year-old Taniam died due to "blunt trauma on head and face", police sources said.
In view of the report, the three people arrested in the case earlier and charged with assault may now face murder charges, they said.
Taniam, son of Arunachal Pradesh Congress member of Legislative Assembly Nido Pavitra, was allegedly beaten up by some shopkeepers in Lajpat Nagar area of south Delhi on January 29 when he retaliated after they made fun of his hairstyle. He was found dead in his room next day.
The initial post-mortem report had not revealed "much injury or aberration" on his body.
His death had triggered protests in the capital with people from the Northeast alleging racial discrimination against those from the region.
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