Maria Diaz, 78, was killed in her own home above a deli on Hillside Avenue on Wednesday night.
Police say her son, Osvaldo Diaz, has an extensive criminal history and has struggled with mental illness in the past. He was known to stay with his mother.
Maria Diaz was found after her daughter hadn't heard from her and became concerned.
She was discovered lying on the floor of her bedroom with a severe laceration to the back of the head.
Forensics recovered from the scene included bloody footprints and a machete.
There were no obvious signs of a break-in at the apartment. It also did not appear that anything was taken from her home.
Osvaldo Diaz served in the NYPD as an officer for three years, stationed at the Midtown North Precinct, before he was fired in January of 2008.
A former neighbor said the Diaz family used to live next to him in a house a few blocks around the corner from the apartment where she was killed.
He said they were quiet, low-key and kept to themselves.
The crime has rattled the neighborhood, which is lined with homes above businesses.
"It's not good. This is a nice neighborhood," neighbor Deoall Ramdat said. "I've never seen this happen. I've lived here seven years."
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