Sabrina Lal who had fought a long battle to bring the killers of her sister Jessica Lal to book passed away on Sunday evening, her brother said.
Sabrina, in her early fifties, was ailing for long and was suffering from cirrhosis of the liver.
"She was not keeping well and had been in and out of hospital. Yesterday, her condition deteriorated at home and we took her to hospital. Today, in the evening, she passed away. She had cirrhosis of the liver and because of that, many complications arose and she had a multiple organ failure," her elder brother Ranjith Lal told PTI over phone.
Her last rites will be performed on Monday.
Last year, in an interview to PTI, Sabrina had spoken about her plans to start a foundation in memory of her sister to aid women in similar situations to get justice.
She had said that she has forgiven her sister's killer, Manu Sharma, who walked out of jail last year after the Delhi Sentence Review Board recommended his premature release.
Siddharth Vashisht, better known as Manu Sharma, was serving life sentence in Tihar Jail here for the 1999 murder.
"I really do not have anything to say. I am not feeling anything. I feel numb. The only thing I hope and pray to God is that he never thinks of repeating that mistake again," Sabrina had told PTI.
She had in 2018 written to the jail authorities that she had no objection to Sharma's release.
Jessica Lall was murdered in 1999 at a upscale restaurant in the national capital.
Calling Jessica her closest friend, Sabrina had said she missed her sister's presence in her life every day.
"She was jovial and positive in life. It is not just birthdays and death anniversaries that I miss her, it is every day. I have lots of pictures of hers in my home and not that I need them to miss her, but they are there to remind me of her," Sabrina had told PTI.
A film, No One Killed Jessica, was made on Sabrina's fight for getting justice for her sister.