After Carolyn Foster died on Jan. 13 at the age 85 in her Ocean County home, her death was ruled to be due to natural causes. Her age and medical history were cited as factors.

But then a relative came forward and told police Foster’s son had killed her.

The Ocean County Prosecutor’s Office and Manchester Township police reopened the investigation and on Saturday announced they had arrested Thomas Foster, 63, of Manchester Township, and charged him with murder.

Officials said that after the unidentified relative alleged foul play in Foster’s death, the Ocean County Medical Examiner’s Office conducted an autopsy.

“During the examination, it was determined that other contributing factors may have been involved in Carolyn Foster’s death,” the prosecutor’s office said. That prompted Ocean County Prosecutor Bradley D. Billhimer to order the investigation reopened.

“After conducting a thorough investigation, it was determined [Friday] that Carolyn Foster’s 63-year-old, live-in son, Thomas Foster, was responsible for her death,” the statement said without providing details as to what killed her.

Foster was arrested without incident Friday and was being held at the Ocean County Jail pending a detention hearing.

Officials said the investigation was continuing.