The Brooklyn nurse whose duct-taped remains were found propped up in her bedroom closet was still alive and breathing when she was locked inside, it was revealed Friday following her roommate’s arraignment on murder charges.

Kyimar Thein’s hellish death began when she was choked out by Alexander Alberda following a July 18 argument in the apartment she shared with Alberda’s girlfriend, Annika Cansino, newly unsealed court papers say.

He apparently choked Thein after she pushed Cansino, according to the documents.

The two then proceeded to wrap the 58-year-old in a bed sheet, bind her wrists and ankles with duct-tape and drag her in the closet, where they covered her body in suitcases, Cansino allegedly told cops.

Yet the 23-year-old — who also works as a nurse — chillingly added that before they left she lifted the sheet to take a final peak at her roommate and discovered Thein was still breathing.

Unfazed, the documents say the couple simply locked the closet door and departed.

Thein’s remains were found three days later on July 21, a piece of duct tape still adhered to her mouth.

Cansino remained silent Friday as she was arraigned on charges of kidnapping and murder.

In addition to sharing the Prospect-Lefferts Garden home with Thein, Cansino worked alongside her as a nurse at SUNY Downstate Medical Center, prosecutor Wilfredo Cotto told the court.

Brooklyn Criminal Court Judge Michael Yavinksy ordered the woman held without bail.

Alberda was also ordered held without bail following his arraignment later Friday on the same charges.

Alberda and Cansino are due back in court Oct. 31.