Father Clements served as priest at Holy Angels Church in Bronzeville on the South Side for more than 20 years before he passed in November.
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Clements' impact reached far beyond his hometown of Chicago.
In 1980, he blazed a new trail for Catholic priests as the first to adopt a child. In all, he adopted four sons.
The memorial Sunday was hosted by his adopted children at Saint Sabina Church, 1210 W. 78th Place.
Last August, Cardinal Blase Cupich asked Clements to step aside from the ministry following allegations of sex abuse dating back to 1970s.
Clements called that accusation "totally unfounded."
The Chicago Archdiocese confirmed that the investigation will continue despite his death.
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Clements was a civil rights activist, marching with Dr. Martin Luther King, Jr., in Chicago, Alabama and Mississippi.
He also created One Church One Child to find adoptive homes for many more African American children in Illinois.
The organization has since expanded across the country.