US-based PhD student Maryam Fatima also hit out at a section of the media for running a "trial" against Mr Khalid, the alleged organiser of an event against Afzal Guru's execution at the JNU, saying it is creating a "lynch mob" climate.
Mr Khalid, a former member of ultra-Left students outfit Democratic Students Union, has been missing since the JNU row broke out and police is on the lookout for him.
"Most channels have been conducting media trials based on false information. They first claimed there was an IB report linking Umar to Jaish-e-Muhammad (JeM). This was denied by the IB. But the story is still doing the rounds. All of this is adding up to a lynch mob climate," said Ms Fatima over email.
Her brother, who is working on his PhD on tribal rights and colonial forest policy, has placed his concern for the dispossessed over his own life and career - turning down opportunities to go abroad, she claimed.
She said he has been actively campaigning for the rights of the marginalised and alleged that anti-India slogans at the controversial event at the JNU were raised by Akhil Bharatiya Vidyarthi Parishad (ABVP) activists.
"The issue of sloganeering is shrouded in a lot of fabrications and lies. Several of the videos were doctored," she alleged. "It is ridiculous to ask us if we think it (anti-India slogans) is okay - of course, not. But you have to dig deeper and see who was raising them. He is a true son of India," she said.
Ms Fatima, who is the eldest among five sisters, but younger than their brother Mr Khalid claimed that even her 12-year-old sibling has received "violent threats" on social media.
"My sisters received threats on Facebook when they first started posting in defence of Umar. They are not going to school or college. There are also the posters in Munirka directly calling for Umar's death. As you can imagine, we feel very vulnerable right now," she said.
The family is "not in touch with" Mr Khalid since he went missing, Fatima said, and could last speak to him after his television interviews with two channels. "We are really worried for his safety."
She claimed the allegations about Mr Khalid's links to Pakistan, terrorists and JeM are absolutely false and that he does not even have a passport.
On their father SQR Ilyas' past links with Students Islamic Movement of India (SIMI), a banned outfit, Fatima said that he left SIMI in 1985, way before it was banned in 2001 and Umar's birth.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
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