The Somerset County Prosecutor's Office announced Thursday afternoon that a post-mortem examination determined that a 45-year-old Bernardsville resident had drowned her 4-year-old daughter in the home's bathtub before killing herself.

Somerset County Prosecutor Geoffrey Soriano said Allison Hawthorne, 4, was the victim of homicide as a result of drowning in the bathtub in an upstairs bathroom.

Both lifeless bodies had been discovered by the child's father last Thursday evening inside the bathroom of the Roundtop Road home.

A preliminary evaluation conducted by the Regional Medical Examiner’s Office has determined the cause of death of Patricia A. Graham-Hawthorne, 45, is that she committed suicide by ingesting paint thinner and drowning herself, the prosecutor announced. The investigation had been conducted over the past week.

Given the Medical Examiner’s conclusion as to the manner of death, as well as the criminal investigation to date, it has been determined that Graham-Hawthorne murdered her daughter before taking her own life last Thursday, according to the prosecutor.

Soriano said in a news release that Bernardsville police officers responded to a 911 call dispatching them to the Hawthorne residence for a report of a deceased child. 

When officers arrived, the mother and child were found deceased in the upstairs bathroom, authorities said. Officers were told by the husband and father of the dead woman and her child that he had arrived home from work at approximately 6:35 p.m., and discovered his wife and child unresponsive in the bathtub. At that point, he called 911, he told police.

The father and husband was identified as Robert Hawthorne in an online obituary by the Dooley Colonial Funeral home in Westfield, which handled the services. A mass for the two was held Wednesday at St. Helen's Roman Catholic Church in Westfield, the obituary said.

The police investigation has determined that Graham-Hawthorne had been accessing numerous Internet sites involving methods for committing suicide, authorities said.

During the post-mortem examination, the Medical Examiner noted slash wounds on Graham- Hawthorne’s wrists, water in her lungs as well as an apparent toxic substance in her stomach cavity, according to the prosecutor's office.

According to the obituary, Graham-Hawthorne was a 1984 graduate of Westfield High School.

"Allie was to start kindergarten in the fall of this year. Patty was a homemaker and wonderful mother. Allison was the love of Patty's life and a very active little girl, attending swimming, language and most recently karate classes. Patty was a loving daughter, mother, sister, cousin and friend," the obituary said. 

The obituary said the two are survived by their "loving husband and father, Robert Hawthorne, step children Bobby and his spouse, James, Christopher and Danielle."

Several tributes were posted on the Dooley website. "My family and I are so sad for your unexpected loss," one said. "Patti was such an amazing and loving mother and words cannot capture the spirit of little Allison...We  just found out about the accident and could not be sadder. It has hit like a shock wave. We will always remember the tender moments playing after preschool or sharing a sunny afternoon on the front lawn."