As eyewitnesses watched in horror, 27-year-old Sergio Casian Aguiar of Turlock, told people who urged him to stop late Saturday that the boy was "trash," the witnesses said. He asked for a knife at one point and, at another, said, "Look how they make toys now."

Eyewitnesses tried to stop the man, who swung and slammed the child into the asphalt behind his parked four-door Toyota pickup.

Investigators spent Father's Day trying to understand and cope with the savage attack on Bradbury Road, 10 miles west of Turlock near cow pastures and dairy farms.

The boy's beating left police and rescue workers badly shaken, said Deputy Royjindar Singh. "Why would somebody do this?" Singh said.

"In the shadows and light it looked like he had hit an animal," said Dan Robinson, the chief of Crows Landing Volunteer Fire Department, who came upon the chaos driving home from a late dinner in Turlock, in an interview with the Modesto Bee. "As we backed up again, I could see that he had blood on his arms. I could see that it was a small child."

Robinson jumped from his vehicle and confronted the man, who lunged at him. Robinson said the man wasn't screaming and wasn't loud, but was forceful, saying "demons" were in the boy.

"Give me the knife. Give me the knife," the man said as he grabbed for a pen in the firefighter's front pocket.

"There was a total hollowness in his eyes," Robinson said, "like I could see right through to the back of his head."

An elderly couple was first on the scene, calling 911 about 10:15 p.m. to describe the terror unfolding before their eyes.

The man ripped the child out of a car seat in the back of a pickup truck, threw him to the ground and kicked and stomped him against the pavement, witnesses told deputies. At least three people yelled at the man and attempted to pull him off the boy, but were brushed back by the attacker.

Coroner's deputies believe they know the boy's name, but "due to the severity of his injuries making a visual identification is nearly impossible," Singh said.

Authorities were attempting to contact family members on Sunday, but Singh said many live out of the area.

A Stanislaus County sheriff's helicopter flying in the area on another matter arrived about six minutes after the initial 911 call. Officers in the helicopter could see the man beating a child on the road, and because patrol deputies were still several minutes away, they decided to land in a field near the man's vehicle, Singh said. "When the flight officer first contacted the suspect and tried to get him to stop, the infant was on the ground and the suspect was kicking and stomping the child," Singh said.

The helicopter's tactical flight officer, Modesto Police Officer Jerry Ramar, standing in a cow pasture behind an electric fence, ordered Aguiar to stop at gunpoint. Aguiar raised his middle finger and continued his attack. Officer Ramar shot Aguiar once in the forehead, the witnesses and police said. Aguiar died at the scene.

The toddler was taken to Emanuel Medical Center in Turlock, where he was pronounced dead shortly after arrival.

"Some of the key questions we're trying to answer is why this happened?" Singh said. "What was going on before the suspect left? Where was he going? Where had he been? What was going on in his life that day?"

Stanislaus County Sheriff Adam Christianson sent department employees an e-mail Sunday offering assistance to any staff member affected by the incident, Singh said.

"It does hit home, especially for the deputies with children and those officers in the helicopter that attempted to save the boy's life," he said. "This is one of the more violent scenes they've ever seen. It involves a victim who is defenseless and helpless. And it's Father's Day."

Isabelle Thomas, who lives a few hundred yards from the scene, was working at Emanuel Medical Center, a nurse in the surgical unit, when her son called her with word something bad had happened. Soon she heard of the little boy who died 500 yards from her front door.

"I couldn't go to sleep," she said. "I couldn't rest without seeing it and all that blood. I couldn't believe all that blood."

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**UPDATE**Man who killed son wasn't using drugs

TURLOCK – Toxicology tests showed a Turlock man who beat and stomped his 2-year-old son to death on the side of a dark road wasn't using drugs.

The Stanislaus County coroner said Sergio Aguiar, 27, didn't have drugs or alcohol in his system that might have explained his behavior.

He was fatally shot by police on June 14 after ignoring orders to stop attacking the child. The boy died from injuries to his head and face.

Investigators and co-workers said Aguiar, who worked in a market, had no criminal history or signs of mental illness.