Girl Died of Gunshot Before Being Hit by Car : Killings: Autopsy shows wound to head of handicapped daughter by distraught mother was the cause of death.

Four-year-old Dianna Phan had already died of the gunshot wound inflicted by her mother when the pair were run over by a car on the Garden Grove Freeway, according to autopsy reports released Wednesday.

Stacy Phuong Phan, 32, who had shot her handicapped daughter in the head Monday before lying down with her in front of freeway traffic, died from massive injuries suffered when they were run over, Sgt. Douglas Morrill said.

Four handwritten suicide notes were found in the park where the shooting occurred, but they provided few answers to disturbing questions raised by the murder-suicide.

Why did Phan shoot the child at the park and then drive 6 miles to the freeway to be run over? Where did she get the .22-caliber revolver that she used to kill her child? And why did she use that gun when her family already has a .32-caliber revolver at home?

In her letters to relatives, Phan only stressed that she was seeking escape for herself and the child, said Phuong Chi Lam, Phan’s older sister.

Phan had been distressed and guilt-stricken since Dianna was born brain-damaged, which resulted in the girl not being able to walk or talk, according to relatives. Her depression worsened a month ago when doctors said Dianna had lost her sight.

Family members reported mother and daughter missing about 11 p.m. Monday, and they were dead when police found them on the freeway at 11:48 p.m.

“She wrote a lot,” Lam said. “She left instructions. She wanted to free herself and make it so the baby would no longer suffer.”

The notes were addressed to her husband, parents, sisters and a brother-in-law to be.

“They were basically suicide notes,” Morrill said. “She wrote that life has been hard since Dianna has been born, and that was the only thing that alluded to the deaths.”

In the letters, Stacy Phan thanked her relatives for being supportive and wrote that she loved them. She also instructed her husband to get money from a safety deposit box, notify the savings and loan where she worked and get in touch with Dianna’s school.

From January until August, the girl had been attending Mark Twain Special Center in Garden Grove for disabled youths ages 3 to 22, said her father, David Da Phan.

But she was constantly hitting herself on the head at school and would come home with bruises. The family decided that Dianna would be more carefully watched at home. Stacy Phan’s parents and two older sisters had recently emigrated from Vietnam and lived with her.

Police said they are still tracing the gun Stacy Phan used. Authorities have yet to find the driver, who did not stop and who might not have known he had run over the two. Witnesses with information are asked to call (714) 741-5800.