Treffly Coyne was out of her car for just minutes and no more than 10 yards away.

But that was long and far enough to land her in court after a police officer spotted her sleeping 2-year-old daughter alone in the vehicle; Coyne had taken her two older daughters to pour $8.29 in coins into a Salvation Army kettle.

Minutes later, she was under arrest — the focus of both a police investigation and a probe by the state's child welfare agency. Now the case that has become an Internet flash point for people who either blast police for overstepping their authority or Coyne for putting a child in danger.

The 36-year-old suburban mother is preparing to go on trial Thursday on misdemeanor charges of child endangerment and obstructing a peace officer. If convicted, she could be sentenced to a year in jail and fined $2,500, even though child welfare workers found no credible evidence of abuse or neglect.

On Dec. 8 Coyne decided to drive to Wal-Mart in the Chicago suburb of Crestwood so her children and a young friend could donate the coins they'd collected at her husband's office.

Even as she buckled 2-year-old Phoebe into the car, the girl was asleep. When Coyne arrived at the store, she found a spot to park in a loading zone, right behind someone tying a Christmas tree onto a car.

"It's sleeting out, it's not pleasant, I don't want to disturb her, wake her up," Coyne said this week. "It was safer to leave her in the safety and warmth of an alarmed car than take her."

So Coyne switched on the emergency flashers, locked the car, activated the alarm and walked the other children to the bell ringer.

She snapped a few pictures of the girls donating money and headed back to the car. But a community service officer blocked her way.

"She was on a tirade, she was yelling at me," Coyne said. The officer, Coyne said, didn't want to hear about how close Coyne was, how she never set foot inside the store and was just there to let the kids donate money, or how she could always see her car.

Coyne telephoned her husband, Tim Janecyk, who advised her not to say anything else to police until he arrived. So Coyne declined to talk further, refusing even to tell police her child's name.

When Janecyk pulled up, his wife already was handcuffed, sitting in a patrol car.

Crestwood Police Chief Timothy Sulikowski declined to comment about the case. But he did not dispute the contention that Coyne parked nearby or was away from her car for just a few minutes.

He did, however, suggest Coyne put her child at risk.

"A minute or two, that's when things can happen," he said.

Talk about the case has intensified, particularly online, where bloggers are weighing in on various message boards.

Many have harsh words for the police department, calling the arrest of a mother who left her child in a locked car for a few minutes an abuse of authority.

Yet statistics show thousands of children are injured and dozens die every year after being left unattended near or inside vehicles.

"I am talking tens of thousands of people who leave their kids in the car for any period of time all around America," said Janette Fennell, founder and president of Kansas-based Kids and Cars. "People don't appreciate the dangers of leaving a child alone in the car."

Coyne's attorney, Michelle Forbes, argued that Coyne did not break the law any more than a mother who parks in front of a school in a rainstorm and leaves an infant in the car as she runs a few feet to pick up another child.

"As long as the car is not out of her sight, then the child is not unattended," she said.

Coyne and her husband believe she is unfairly being lumped in with parents who put their children's lives at risk.

"If I were going on a shopping spree then, yes, I would deserve arrest," Coyne said. "I was standing right there. I never went into the store.

"I'm a great parent."