Chona Manzano and her son Gabrial were stabbed to death in their Evanston home on May, 2013.
In Court of Queen's Bench on Wednesday, Clorina pleaded guilty to first-degree murder, second-degree murder and sexual touching of a minor.
Originally, Clorina was charged with two counts of first-degree murder. He also faced charges of sexual assault of a 15-year-old girl over a three-year period. Child pornography charges were also laid in the months following the killings.
There is a ban on naming the teen involved, but according to sources familiar with the case, she was pregnant.
Court documents show Manzano may have learned about the inappropriate sexual relationship before her death.
A date for a sentencing hearing will be set next week.