The footage came from a police surveillance camera in the 1200-block of North Mason Avenue. It captured the shooting that killed 24-year-old Brittany Hill last week.
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Hill was with her 1-year-old daughter and died shielding her baby. Hill's daughter was not injured.
"She was mine. She was my baby," said James Hill, Brittany's father. "She did what she thought was best and she died."
Two men from Urbana, Michael Washington, 39, and Eric Adams, 23, have both been charged with first-degree murder in the shooting and have been denied bond. Prosecutors said that Brittany's daughter smiled and waved at the suspects before they opened fire.
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It was only days after the charges were filed that the video leaked.
"On Sunday morning, June 2nd in church, her family was brought a video showing having to re-live her graphic death from the past week," said Ja'mal Green, friend.
"It restarted everything and I had to go back out and they're hurting even more because everyone is calling, 'You see the video? You see the video?'" Hill said.
The video had been released on social media without the family's consent.
"Her 7-year-old son had to look at the phone and say 'What is this video?' and see the acts of two violent criminals on his mother," Green said.
Police have since launched an investigation into who may have leaked the footage.
The family and its attorney announced the lawsuit Thursday morning.
"Someone did something they should not have done," said Hill. "There needs to be a change in the system and someone needs to be held accountable."
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A spokesperson for the Chicago Department of Law said Thursday, ''We have not yet received the suit and therefore cannot comment.''
Brittany's family said they plan to lay her to rest this weekend.
"She made me proud, she made me proud because she gave her life in the same way I would have gave my life," James Hill said. "That was my baby."