A Scarsdale man allegedly stabbed and beat his disability advocate mother to death inside their nearly $2.5 million home in the tony town — marking the first homicide in the nation’s wealthiest suburb in a decade.

Chester Green, 26, was arrested and charged with second-degree murder for killing his mother, Marian Green, 71, at their home in the Fox Meadow region of Scarsdale earlier this week, according to the Westchester County District Attorney’s office.

Chester allegedly killed Marian sometime between Sunday and Tuesday by stabbing and beating her multiple times with a sharp object and a blunt instrument, prosecutors alleged.

The alleged killer son was taken to the White Plains Hospital after Scarsdale police found him standing outside the three-bedroom, multi-million dollar house on Butler Road. Police later responded to a call for help and discovered Marian dead inside, Lohud reported.

A motive in the disturbing attack is not immediately known.

Marian was a widow and lived alone with her adult son on the quiet, tree-lined street, according to local reports.

She was a staunch advocate for disabled people and special needs children, and acted as the chair of the village’s Advisory Council for People with Disabilities, Lohud reported.

Marian also frequently attended Village Board meetings to ask for more accessible sidewalks and local pools, Scarsdale10583.com reported.

“Like everyone in this county, I am shocked at the horrifying death of Marian Green and the manner in which she was killed. This tragedy is only further compounded by the familial relation between the victim and suspect in this case,” Westchester County District Attorney Susan Cacace said in a statement.

“My office has charged Ms. Green’s son in connection with her murder, and we will seek to ensure that justice is achieved for her through this prosecution. May she rest in peace.”

Scarsdale was ranked the wealthiest suburb in the US for the third year in a row this year, boasting a whopping average income of $612,591 a year, according to a recent report.

Homicides are exceedingly rare in the ritzy town, with the last known being the murder of pediatrician Robin Goldman in 2016.

Her husband, Julius Reich, was sentenced to 20 years in state prison in 2018 for stabbing the mother to death while she was showering.

Chester was arraigned virtually on Wednesday afternoon and ordered held behind bars. He is slated to return to court on Aug. 5.