It began as a request from a 9-1-1 dispatcher that's about as low-key as it gets. A welfare check means a cop swings by a scene to make sure everyone's OK. Last year, police answered more than 18,000 such calls in Portland.

Most were forgettable. Except for one.

Like all people, cops discuss politics, sports and current events when they gather. Eventually, though, their conversations turn to the job and the mysterious world-within-a-world where they work. Stories full of humor, drama and even absurdity spill out.

But given time, the mood changes and they talk about their ghosts.

"You start this job and everything's exciting," said Matt Nilsen, a 41-year-old assigned to the

. During a typical year, Nilsen, whose father was a cop, handles about 400 calls. During his 18-year career, that adds up to roughly 7,200 calls.

"Nothing fazes you at first," he said, sitting up against a table where officers fill out reports at the end of the shift. "In time, something changes. You learn you have to compartmentalize."

Cops try to forget. But often they can't.

"Sometimes when I'm on patrol I'll think about that boy," Nilsen said. "Maybe, I see a kid on the street. Or I'm at coffee with some officers and they'll ask me if I ever knew what happened to him."

The strange thing about trying to forget is what you remember.

"His name," Nilsen said. "I'll never forget this name."

***

Officer Matt Nilsen

Last Halloween, about 90-minutes into his shift, Nilsen took a break from patrol and met two other officers at a coffeehouse. While inside, their portable radios crackled with a call. It was about 8:30 a.m. The dispatcher requested a welfare check at a Southeast Portland home.

When Nilsen arrived, he learned a woman had called 9-1-1 to say she'd received a voicemail from her friend's father. The dad lived in Vermont and for the past two days had been unable to reach his 40-year-old daughter, so he called her friend to see what was going on.

The friend went to check on Micaela Quinn and found the front door to her home unlocked. When she stepped inside, she spotted Quinn lying on the living room floor.

Soon, additional officers, detectives and medical authorities came. They determined Quinn, who they later learned battled a series of on-going medical issues, had died of natural causes.

"The little kid had been in the home for two days," Nilsen said. "He was all alone with his mother's body."

For a moment, Nilsen fell silent.

"You know what I remember?" he asked before answering.

"I walked in that home and the first thing I saw was that boy's blond hair," he said. "I have three kids, including a 2-year-old girl. His hair curled just like my daughter's, you know right before they get a haircut."

The boy was dehydrated and hungry, sickly and lethargic, and a police supervisor requested an ambulance take him to the hospital. Another call was made to Oregon Department of Human Services, which would take the boy into protective custody until family could be located.

Paramedics loaded the boy into the ambulance. In his patrol car, Nilsen followed to Doernbecher Children's Hospital. On the way, he thought less like a cop and more like a father.

"Two days in a home with his dead mother," he said. "What did he think about? Imagine how scared he was. What was it like at night? Did he cry for her? Did he try to wake her up?"

Even more haunting was the boy's future.

"What will he remember?" Nilsen asked. "I hope he forgets."

After an exam, nurses gave the boy a bath, tucked him into a bed and gave him some grape juice. The staff assured Nilsen that the boy would be OK. Technically, the call had ended and hospital officials said Nilsen was free to go.

Instead, he pulled a chair up alongside the boy's bed and sat down. He knew this child would be one of his ghosts.

"I just rubbed his head," Nilsen said. "I held his hand and prayed that he'd be taken care of and find peace."

When his shift ended that October afternoon, Nilsen returned to the precinct and filled out reports before walking upstairs to his locker, where he changed into his civilian clothes. When he got home, his wife asked how his day had been. He wasn't sure how to answer. Like most cops, he tries to wipe his feet clean to avoid tracking the dirt of what he does into the home.

Fine, he said, just fine.

The next morning, when he was in the kitchen, Nilsen said another prayer for the boy. When his wife walked in, she told her husband that he didn't seem himself.

"I broke down right there," he said. "I began crying."

***

The boy now lives with his grandfather on the East Coast. He's doing well. But his grandfather said he wonders about the lasting impact of those two days spent alone in that home.

So, too, does the cop.

But the calls keep coming.

When a gunman opened fire in Clackamas Town Center last December, Nilsen raced there to help customers escape. As dramatic as that scene turned out to be, the routine call with the boy is the one Nilsen knows he'll carry with him long after his career ends.

Last Wednesday, he was starting his early-morning shift. He gathered his gear and was ready to head into the precinct garage, when he stopped to offer a final thought about that October morning.

In the years to come, the details will fade: the time the welfare check came in, the home's address and perhaps even the names of the other officers who responded. What will stick with Nilsen is a simple image: a little boy, same age as his daughter, with curly blond hair and an uncertain future.

He moved to a thick metal door that led to the precinct's garage. He opened it and then paused.

"I'll never know," he said. "But I'll never forget him."

The door slammed shut and he was gone.