HORSHAM, Pa. (AP) — A mother has been charged with murder in the death of her 11-year-old son in southeastern Pennsylvania and is awaiting extradition from New Jersey, where she was arrested after her SUV was found in the surf on a beach at the Jersey shore.

Ruth DiRienzo-Whitehead, 50, of Horsham, is charged in Montgomery County with first- and third-degree murder as well as possession of an instrument of crime in the death of Matthew Whitehead, prosecutors said Wednesday.

Prosecutors said the boy’s father found the door to the master bedroom in the couple’s home locked Tuesday morning and his wife and their SUV missing. He then found their son unresponsive in the bed, where he had gone to sleep with his mother. Police were called and declared the boy dead.

An autopsy Wednesday concluded the boy’s death was due to strangulation and the manner of death was homicide.

Prosecutors allege DiRienzo-Whitehead killed her son after he went to sleep at about 9:30 p.m. Monday and then drove the family SUV about 120 miles (193 kilometers) south to Cape May, New Jersey, where she drove the vehicle “into the ocean just off Beach Avenue.”

After the vehicle was no longer operable, she walked to Wildwood Crest, a Cape May borough, where she was taken into custody by Wildwood Crest police and interviewed by Montgomery County detectives and Horsham police, prosecutors said.

Authorities allege in a criminal complaint that DiRienzo-Whitehead told investigators her son had been upset and “crying off and on all day” over the family’s financial difficulties and that she strangled him so he would not have “to grow up with these struggles.”

DiRienzo-Whitehead is being held in Cape May County and will be extradited back to Montgomery County, Pennsylvania for arraignment on the charges, prosecutors said Wednesday. Court documents don’t list an attorney representing her and a message could not be left at a number listed in her name.

A neighbor, Ed Smith, told WFMZ-TV that the boy’s death was “very tragic” and the case was “surprising.”

“Very nice people. Good neighbors,” he told the station. Smith and his wife, Diane, said they have known the boy’s mother for more than four decades.