SAN DIEGO — A tow-truck operator killed himself by tying a weight to his neck in the family swimming pool, and his wife and two daughters were forcibly drowned, according to an autopsy report released Wednesday.

Alfredo Pimienta, 44, was found fully clothed, with his hands secured behind his back with rusty handcuffs and a yellow rope tied around his ankles. His head was weighted down by a tow hitch attached to a wire around his neck.

Investigators found his youngest girl was drugged and bruised. The elder girl and wife had several blunt force injuries.

"Throughout the home there were multiple items with written instructions indicating whom to call, wishes for body disposition, and other notes of a suicidal nature, all appearing to have been written by the parents," the report said.

The autopsy shed no light on a motive for the May 24 murder-suicide. Police have said the family was in financial distress and both parents planned the deaths.

The body of 38-year-old Georgina Pimienta was found clothed in a bathtub inside a locked bathroom, submerged in about 10 inches of water with paper obstructing the drain. Investigators detected a sleep medicine, zolpidem, in her system, likely administered by her or her husband.

She suffered bruises on her head, neck, torso, wrists and legs, the autopsy said.

Priscilla Pimienta, 17, was likely bound by one or both of her parents when she was drowned, the report said. Her body was also found in the swimming pool. Her wrists showed bruises that suggested she may have been handcuffed.

Her high school graduation dress was found in a garment bag on a couch inside the home with a handwritten note that read, "for funeral."

Emily Pimienta, 9, was found in a hot tub near the pool, and investigators found a "markedly elevated" level of acetaminophen and other medications in her blood. The report said the drugs didn't contribute to her death and suggested they were intended to sedate her before being forcibly drowned.

The autopsy does not say in which order the parents and children died.

Alfredo Pimienta called his nephew the night before the bodies were discovered to say that he was transferring business accounts to him, the report said. He asked the nephew to come to his home in the city's modest Paradise Hills neighborhood the next day at 5 a.m.

The nephew thought the call was odd and considered calling police. He arrived the next morning to find corpses in the pool.