How Emmett Till's Mother Turned Her Personal Tragedy into a National Movement: 'She Had a Job to Do'

Emmett Till, a black teen from Chicago, was visiting family members in Mississippi in the summer of 1955.

There, the 14-year-old boy was kidnapped before being beaten, mutilated and lynched by two white men after a woman falsely accused him of lewd behavior.

The woman accused Till of whistling at her and attempting to grab her hand and waist.

A large metal fan was tied to his neck with barbed wire and he was tossed in the Tallahatchie River.

Months after Till's death, the killers, Roy Bryant and his half-brother, J.W. Milam, were acquitted by an all-white jury.

After her son's death, Till's mother, Mamie Till-Mobley, fought to have her only child's body brought home to Chicago. At his funeral, she ordered that his casket remain open so all could see what happened to her son.

Her decision became a turning point for the civil rights movement and propelled her to become a crusader for justice for her son and for others.

Her story, from government worker to civil rights activist and educator, is explored in a new docuseries called Let the World See, which premieres on ABC Thursday, Jan. 6, at 10 p.m.

The series features actress and producer Nia Long as the voice of Till-Mobley, and includes commentary and historical analysis from prominent figures like former first lady Michelle Obama. (An exclusive clip is shown below.)

"I often heard [Till-Mobley] say, 'Well, what do I have to lose? They've taken everything from me,'" her cousin Ollie Gordon tells PEOPLE. "That was the motivation to pick up the torch and continue to fight and advocate for justice and advocate for peace for her son. Not just for Emmett, but for all of the lives that have been lost at the hands of bigotry and racism. That was her fight, that was her mission."

Gordon hopes that those who watch the documentary will come away with a better understanding of what happened and "how deep hatred and racism penetrates and how hurtful it is," she says. "They have families, they have mothers and children and father's and the pain is pain."

Gordon witnessed the pain herself. She was 7 years old when Emmett died.

"I still get emotional and I still cry when I think about it or I see pictures and I see her and I see her pain and I feel her grief," she says.

Gordon also remembers the bond between the mother and son — how Till-Mobley used to drive around the neighborhood looking for Till when it was time for him to come home on a night and battle him about washing his ears.

"It was always a fight about him washing his ears," she recalls. "It was just a thing about his ears and keeping his ears clean, because his mom was very meticulous."

For more on the brutal murder of Michael Shaver and the case against Laurie Filmer, subscribe now to PEOPLE or pick up this week's issue, on newsstands Friday.

Gordon says Till-Mobley, who taught special education in Chicago, kept up her fight for justice throughout her life — up until the day she died in Jan. 2003.

"She was on dialysis near the end and she was weak but she was still traveling and still speaking," she says. "The night that she died she was going to dialysis, and on her way to a speaking engagement that next morning. Until the day she passed away, she was still carrying that torch. And I know at times she did get tired, but she said she didn't have time to be weary. She had a job to do and she had little time to do it."