Everett wore nothing but a diaper, blue lips gripping his pacifier.

Or so it seemed to Don Hudson, who watched the paramedics, hunched over the warm asphalt, trying to revive the 4-month-old in El Cerrito on Monday.

A bouquet of white peonies rested beside parking stall 437 the next day.

"I thought it was a girl at first, he was just wearing Pampers. He had light brown hair. He was a big kid for his age," said Hudson, who commutes daily through the El Cerrito Plaza BART station. "The two paramedics were young people. They were obviously freaked out."

Authorities continued to investigate the death of Everett Carey, one day after his mother found him dead inside the family car at the station, but made no decision Tuesday about whether to pursue criminal charges.

The father, Alan Carey, apparently forgot to drop off his son at day care Monday morning. He left Everett in his car seat when he parked at BART to commute to his banking job in San Francisco, BART police Lt. Frank Lucarelli said.

The mother, Anne Carey, found Everett unconscious inside her husband's silver Chrysler about 5:30 p.m.

"Anything the criminal justice system could do to this couple pales in comparison to what they are doing to themselves," Lucarelli said. "It's hard to imagine how tortured they must be right now."

Contra Costa District Attorney Robert Kochly said his office had not reviewed the police investigation as of Tuesday, and he could not say whether the case warrants prosecution. Lucarelli said his detectives interviewed the parents Tuesday but made no decision about whether to arrest anyone.

"We need to get a sense of whether this is a situation where this could have happened to anyone, or a situation where someone was selfish and grossly negligent," Kochly said, adding that about half of similar cases nationally have been prosecuted.

County prosecutors declined to charge the father of an 11-month-old who perished in a car outside the father's Concord workplace in 2007. That situation involved a change of routine and a father who had been under a lot of pressure, Kochly said. Santa Clara County prosecutors did charge a father in the death of a 5-month-old left in a car in 2001, while the father watched a cartoon inside a house. A jury convicted him of involuntary manslaughter.

Lucarelli said he did not know whether the child's day care called the family to ask why Everett had not been dropped off. Anne Carey went to BART after not finding her child at day care, police said.

Paramedics took the baby to Doctors Medical Center in San Pablo, where he was pronounced dead at about 6 p.m.

A man who answered the door at the family's El Cerrito home declined to comment Tuesday.

"When you're going to work, you're on autopilot. Another part of your brain takes over," said Janette Fennell, founder of the nonprofit Kids and Cars, which researches non-traffic-related child deaths in cars. "It's really a lot more common than many people imagine."

While air temperatures in El Cerrito reached the high 60s Monday, the temperature inside the vehicle likely surpassed 100 degrees, Fennell said. When exposed to such high heat over a long period, small children often develop hyperthermia, or heat stroke.

Twenty-seven children 14 and younger die in the United States every year of heat stroke after being left in cars, according to a report released Tuesday by the National Highway Traffic Safety Administration. But Fennell says her group's research suggests the figure is actually 37 children per year.

Everett was the first such victim in California this year but the second in two days nationally. On Sunday, 3-year-old James Lymburner went missing for several hours from his family's Warwick, R.I., home. His family found him inside a car parked outside the home.

Staff writers Malaika Fraley, Roman Gokhman and Robert Salonga contributed to this report. Reach Karl Fischer at 510-262-2728 or kfischer@bayareanewsgroup.com. Reach Shelly Meron at 510-243-3578.