Both victims were found in the home on Ampere Avenue in the Spencer Estates section after the fire broke out just before 7:45 a.m.
The fire was already burning out of control when firefighters arrived.
The house was already filled with deadly smoke.
Suddenly, flames burst through the front door as firefighters pushed their way-in desperate to reach the victims, but only one of them could be saved.
Marshalls and NYPD detectives spent hours sifting through the ruins of the family's kitchen where the fire is believed to have started.
Neighbors watched from the street and shook their heads in disbelief.
Chris Marrero was one of three men who tried to help.
"We kicked the door open, but there was no way could get in," neighbor Chris Marrero said. "The smoke was keeping us back, and there was absolutely no way to get in."
Witnesses last saw 84-year-old Paula Aglira in her bedroom window, begging firefighters to save her severely mentally-disabled, 45-year-old son, Michael, but she quickly disappeared in the smoke.
Firefighters were unable to save her and authorities said Michael had burns across more than half his body.
It's a fire that was all the more tragic because Mrs. Aglira had devoted much of her life to caring for her son.
The fire was a close call for residents of the adjoining home.
"Thank God we're okay," said Luisa Marrero, a neighbor's relative.
Luisa Marrero was visiting her grandchildren when the fire broke out.
The cause of the fire is under investigation.