CHICAGO (CBS)–It was March 4, 1999 when three young children died in Naperville at the hands of their mother, Marilyn Lemak.

Lemak is serving a life prison sentence for killing her kids– Nicholas, 7; Emily, 7; and Thomas, 3 – in her Naperville home two decades ago.

(Illinois Department of Corrections)

DuPage County prosecutors allege she drugged and suffocated the children.

Lemak suffered from depression at the time of the murders. In the only interview she’s given since her conviction, in 2012 she spoke to French TV station M6 and blamed the murders on depression and divorce from her husband.

She’s serving out her life sentence at the Logan Correctional Center in Lincoln, Illinois.