LIVERMORE — A quiet, country drive through Del Valle Regional Park Saturday ended abruptly for Livermore police Chief Michael Harris, who braked for a bloodied woman screaming “Take him, take him!” before thrusting a wounded child into his arms.

The San Jose mom, identified as 23-year-old Ashley Newton, handed off the unconscious, blond baby, half-dressed in a Cookie Monster diaper and blue, striped pullover shirt. The disheveled woman then tried to get into Harris’ vehicle, where his own 2- and 3-year-old girls sat quietly in their car seats.

“She thought we were going to take the baby and go to the hospital — she was in a really bad place; you could tell,” said Harris. “She handed me her baby, and asked me to help her baby — she thought he was still alive.”

Harris, who was off-duty and exploring the park with his family when he encountered Newton, clung to hope that these thoughts were true — the police chief, along with a park lieutenant and a California Highway Patrol officer responding to the woman’s crashed car 200 yards away, performed CPR on the wounded infant. As first responders continued their rescue efforts, they noticed the child’s injuries were not wounds received in a car crash — they were deep stab wounds.

Officials pronounced the child dead about 10 minutes later, as his mother sat dazed in the roadway with blood caked on her sweatshirt and torn jeans. Hours later, after being treated for a self-inflicted stab wound to her arm, the woman was booked into Santa Rita Jail ï»¿on suspicion of the murder of her infant son.

Woman ‘appeared’

The incident began at 10:30 a.m. Saturday, when officials inside the 4,400-acre park received a report of a gray Honda Civic crashing repeatedly into large rocks near Camp Arroyo, officials said. The responding CHP officer originally assumed that the vehicle, which had extensive front- and rear-end damage, had been damaged by a hit-and-run driver but decided to investigate further when he noticed a baby seat in the back.

Harris and his wife passed the wreck on their way up Arroyo Road but continued onward since CHP was already on scene. When they came upon the road’s dead-end, they turned around past the Arroyo campground and headed back from where they came.

“All of a sudden, this woman just appeared in the roadway in front of me with the baby,” Harris said. “There wasn’t much time to think about it, only to react.”

The immediate assumption was that the woman and her child had been injured in the car crash, Harris said. That notion changed the longer they stayed on the scene, assessing injuries, the woman’s behavior and unspecified comments she made.

“She made several spontaneous statements at the scene that implicated her as being the sole person responsible,” East Bay Regional Park District police Sgt. Tyrone Davis said. Harris noted that she seemed paranoid, and like she wasn’t in her right mind.

In interviews with investigators Sunday, the woman admitted to killing the child but did not specify a motive, Davis said. Additional unspecified evidence at the scene suggested the woman may suffer from depression, but officials have yet to confirm any clinical mental health diagnosis.

Intentional crash

The suspected murder weapon, a pocket knife, was booked into evidence Saturday afternoon, and investigators believe the stabbing occurred in the time after the woman crashed her car, Davis said. Authorities also believe the car crash was intentional, since a witness saw the car backing into the rocks multiple times.

Detectives on Sunday also interviewed the father of the child, an unidentified San Jose man who last spoke to the woman on Friday, Davis said. The unemployed woman, who is originally from North Carolina, has lived in both Fremont and San Jose and has no other family in the immediate area.

A warrant to search Newton’s car was processed Sunday, and toxicology tests are pending to determine whether drugs played a role in the killing. According to Davis, investigators have ruled out the possibility of a foiled murder-suicide.

In July 2009, the bodies of a Walnut Creek teenager and his mother were found at Mt. Diablo State Park in an apparent murder-suicide.

In that case, Adam Williams, 16, was shot and killed by his mother, Judith Williams, who then turned the gun on herself. The bodies of mother and son were found at the Lookout Point picnic area by park staff closing up that night.

“It’s shocking — it’s not something you expect to come to work and deal with,” Davis said. “And when you’re dealing with a child, it’s just that much harder to cope.”

Staff writer Kristin Bender contributed to this report. Follow Erin Ivie at Twitter.com/erin_ivie.