Sanchez's 15-year-old daughter is being quizzed by police after allegedly confessing to a cousin that she killed them because her mum's boyfriend repeatedly raped her, police said.
The cousin is believed to have called police, who found the decomposing bodies after conducting a welfare check, Pix11 reported.
Sanchez was found dead in a bedroom chair while the body of Nunez was discovered on the kitchen floor.
Both had been stabbed repeatedly, a police source said. A knife was also found in the kitchen, the Daily News reported.
A shell casing is also believed to have been found at the scene in Sheepshead Bay Houses apartment on Batchelder St.
According to the Daily News, the teenager allegedly confessed to killing the pair on December 27. She allegedly accused her mother of ignoring her claims that Nunez had repeatedly raped her, the paper reported.
The girl reportedly went to stay with her father for a few days following the incident, before staying with her cousin.
She allegedly confessed after her cousin became concerned that she hadn't heard from Sanchez for several days.
The teenager was taken into custody and is being questioned by police, the Daily News reported.