Gigi Jordan, the millionaire pharmaceutical executive convicted of manslaughter in the death of her 8-year-old son, committed suicide by putting a plastic bag over her head filled with nitrogen gas, the city’s medical examiner’s office said Wednesday.

Jordan, 62, was found dead inside her Brooklyn apartment at around 12:30 a.m. on Dec. 30 — just hours after US Supreme Court Justice Sonia Sotomayor issued an order that was expected to send her back to prison.

The NYC Office of Chief Medical Examiner ruled the manner of death a suicide on Wednesday. And said the cause was: “Asphyxia by covering of head with plastic bag and displacement of oxygen by nitrogen gas.”

It came more than a decade after Jordan was accused of force-feeding her autistic son, Jude Mirra, a lethal dose of pills in February 2010 inside a luxury suite at the Peninsula Hotel.

During a six-week trial, the mom’s defense argued she killed the boy because she feared her ex-husband was about to murder the him.

A Manhattan jury acquitted her of the top murder count but found Jordan guilty of manslaughter in 2014.

Jordan was sentenced to 18 years in prison — but a federal judge tossed her conviction in 2020 over a procedural misstep.

Jordan was sprung from prison on Dec. 9, 2020, after serving more than 10 years of her sentence. At the time, a federal judge ordered her released to home confinement on a $250,000 bond as her case played out.

The day before she was found dead, Sotomayor issued the order reversing a previous one from Dec. 20 allowing her to remain free on bail while the high court weighed her appeal.

If you are struggling with suicidal thoughts or are experiencing a mental health crisis and live in New York City, you can call 1-888-NYC-WELL for free and confidential crisis counseling. If you live outside the five boroughs, you can dial the 24/7 National Suicide Prevention hotline at 1-800-273-8255 or go to SuicidePreventionLifeline.org.