Joseph Mitchell parallel parks his Ford Explorer in the Huntwood area of Northeast Washington, leaving enough room to pull out quickly — “a little safety thing I do,” he says — and walks under a night sky toward an apartment building hidden from view.

He knocks on the first-floor door of a 15-year-old recently charged with assault with a dangerous weapon.

The teenager is joining about a dozen young offenders Mitchell monitors daily on behalf of the District’s juvenile justice system, supplementing the work of probation officers and social workers. Mitchell and other monitors — described as the eyes and ears of the system — visit the youngsters in school to make sure they’re in class, stop by their homes to make sure they’re in by curfew and sit in court with them to make sure they don’t feel alone. Seven days a week, at all hours, they walk through some of Washington’s roughest neighborhoods and into the lives of troubled youth others might cross the street to avoid.

They do this as part of a job that most people have no idea exists and that now faces competition from a little black box. The city, using a $400,000 grant, has launched a year-long pilot program expanding the use of Global Positioning System devices to monitor juveniles. The devices provide real-time tracking at a lower cost.

With 175 devices at their disposal, juvenile justice officials have until Sept. 30, when the pilot program ends, to weigh the benefits of computerized efficiency against those of human interactions, to ask, among other questions: What is lost when no one knocks on these youngsters’ doors every day? And what is that worth in a time of financial strain?

A GPS device, which costs $8 a day per person, can tell authorities at any moment whether the teen isn’t where he is supposed to be. A monitor, at a cost of $30 a day per person, can tell them why.

On this night, Mitchell isn’t sure what to expect. The teenager’s mother opens the door.

“We need to set a time. You can’t be popping up here at 9,” she says. “I go to bed at 8.”

Mitchell, 46, a former elementary school teacher, brushes off the cold reception with a smile. He then explains his role, how he has to check on the teenager three times a day, and offers to drive the young man to a weekly group meeting at Sasha Bruce Youthwork, the nonprofit where Mitchell works.

“You don’t want to do all that, do you?” the woman asks her son.

The round-faced boy looks up from a computer in the corner of the room. He’s on Twitter. On the wall above him, photos of children, no frames, dangle from pushpins. On the floor below him, a cord stretches from a wall outlet to an ankle bracelet.

He shrugs. “Not really.”

Mitchell is there maybe 10 minutes before the woman hints, not so subtly, that she wants to get back to watching a women’s basketball game. He hands her his card. “Call if you have any issue.”

“What issues I’m gonna have with my son?” she says, “I’m not gonna have no issues.”

Two nonprofit agencies that provide monitoring services for the city allowed a reporter to tag along on the condition that none of the juveniles involved would be identified. Days spent with three monitors show that the job, done well, is not just about tracking juveniles; it’s about developing relationships. It’s not just about knocking on doors; it’s about walking inside.

Gina Bulett is 5-foot-2 and just over 100 pounds, with red hair that falls to her shoulders. Being white, she doesn’t blend easily into the mostly African American neighborhoods of Lincoln Heights, Simple City and Third Place, called by those who live there “Third World.”

But she has a knack for finding young people when they don’t expect her.

That’s how she got the nickname “Jump-out Gina.”

She was 21, a recent graduate of Georgetown University with an international business degree, when she decided to turn her volunteer work with District youth into a job at Sasha Bruce. One of the first teenagers in her caseload was “smart, could be at Harvard if he wanted,” she recalls, “but he was addicted to hustling.” To check on him, she didn’t go to his house or his school, places where she knew she wouldn’t find him.

She went to the street corner where he sold drugs. And she didn’t go just once. She went again and again.

“He wasn’t ready to make that shift,” Bulett, now 24, says, driving away from a place where someone had painted ”RIP Smoke” on a sidewalk. Where is he now? “I think prison.”

That’s the reality of the job: No matter how much time you put into someone, not everyone wants, or is ready, to change.

“Our clients have been through so much trauma it’s hard for them to know and accept something better,” says Bulett, who keeps dress clothes in an office drawer in case a teenager has a job interview.

Of the more than 80 juveniles Sasha Bruce monitored last month, most came from financially strapped households; 86 percent were male; and 95 percent were African American. The youngest was 12; the oldest, 20. For many, the monitors had to take on parental roles, helping enroll them in school, walking them into job interviews or taking them to their first sit-down restaurant. For the 12-year-old, they assembled a picture book of all the officials in his life to help his mother, who is terminally ill, keep them straight.

“You lose all of that,” with electronic monitoring, says Victoria Otchere, the director of Sasha Bruce’s program. On a wall in her office hangs a baby picture. It’s the son of a young man who was convicted of murder — “a robbery gone wrong” was his explanation — who sent Otchere a text message on her wedding day to wish her well. On another wall is a self-portrait, a pencil drawing, of a young man who says he joined gangs in part because he was angry that instead of spending his days as other seventh-graders do he had to bathe and clothe a mother with HIV. He has Otchere on speed dial.

It’s just after noon when Bulett pulls up to a school in search of a young man who was 13 when he was arrested as a passenger in a stolen car and 18 when he was charged with attempted robbery. He slouches outside the building. He doesn’t see Bulett until she’s in front of him.

“Gina, you snuck up on me,” he says. “How did you get up in here?

“If I sneak up on you, it means you’re not aware of your surroundings.”

“Yeah,” he says, “you never know if someone will sneak up on you with a gun.”

Bulett asks if he’s going to band practice that night. He performs with a go-go band that practices at Sasha Bruce’s Eighth Street SE building.

“Nah, I gotta see my girlfriend. She misses me.”

“You’re putting your girlfriend above the band?”

“That’s right!” he shouts, leaning close to Bulett’s face.

To anybody walking by it would seem threatening. He’s about a foot taller than her and twice her weight. She doesn’t flinch. She knows him well, well enough that she’s confident that he’ll be at practice.

He does show up. For two hours that night, he and a half-dozen other young people crowd into a small basement room, jamming to songs with such force that the floor above them shakes.

Linda K. Harllee-Harper, an administrator with the D.C. Department of Youth Rehabilitation Services, which will ultimately decide to what extent to use the electronic devices, said the information monitors can provide is “invaluable.”

But they have limitations. After monitors do night checks, they have no way of knowing whether a juvenile leaves the house. The electronic devices do.

The youths are also supposed to sign a form each time a monitor visits, she said, but some monitors have let teens sign a stack of forms, documenting visits that were never made. The devices don’t lie.

Ideally, she said, the department would use a combination of the two, but tight budgets could force difficult decisions. “In this fiscal climate anything is possible,” she said.

Elwood “Yango” Sawyer tells people that he used to love going to jail.

“Every time I turned around, I was there,” he says.

He was 9 the first time he landed in a detention center, after repeatedly running away from home, and he was in his 50s, sitting in prison for drug offenses, when he decided that he wanted more from life. In between, he spent about 30 years in jail. It’s where he learned to read and write. It’s where he kicked a 34-year drug habit. And it’s where he took a nickname based on an African word meaning “power of a new day,” a name that most people call him to this day.

“If you look at the statistics, I’m not supposed to be alive,” Sawyer says, “but God saved me for what I do today.”

Perhaps more than any of the other monitors, he understands the time it can take some people to change. He doesn’t like to talk about age, but he has the long, gray dreadlocks of a man well into middle age.

“If these kids have been doing things five or six years, you’re not going to change them overnight,” says Sawyer, who has worked as a monitor for the Alliance of Concerned Men for two years. The night before, one of the eight young people he monitors was arrested on a burglary charge. “And he was doing good,” Sawyer says.

It’s 11 a.m. when he signs in at a school on H Street SE to check on two teenagers. One didn’t show up. The other, an 18-year-old with a history of domestic violence, ambles out of class in a black bubble jacket and jeans. He shakes Sawyer’s hand.

“Something about Yango really touches me because he be saying real things, like, ‘Come on man, you don’t want to end up dead. You don’t want your daughter to have no father,’ ” the teenager says. “There was one point in time there wasn’t nobody I wanted to listen to but I listened to him.”

In his pocket, the teenager carries a small laminated card dated 12/18/2010. It’s a certificate of completion for HVAC (heating, ventilating and air conditioning) repair. He says Sawyer encouraged him to find a vocation.

Mitchell, who grew up in Southeast, says monitoring is not much different from teaching. It’s just catching young people at different stages, he says. When he speaks to the teenagers, he doesn’t use words like “right” or “wrong.” He says ”healthy” and “unhealthy.”

“It’s not about fixing people,” he says. “It’s about getting them to understand their value and what they’re worth.”

After about six years on the job, he has come to realize that the job is technically about the juveniles but also about their families.

After meeting the 15-year-old and his mother, Mitchell sits in the darkness of his SUV and describes the two as “receptive.” “She’s probably overprotective and understandably so,” he says. “You don’t want to lose your baby to the streets. Definitely understand that. Definitely.”

It’s the beginning of a relationship, he says. He’s still building trust.

A few nights later, he will stand in an unfurnished living room that smells of roasted pork chops and discuss the end of a relationship.

Mitchell is there because of a youth who landed twice on his caseload, once at 13 and again at 15. The second time, the teen was charged with being a passenger in a stolen vehicle. When the relationship started, the teen’s mother told Mitchell angrily that he was doing too much.

“Got some good news and some bad news for you,” Mitchell tells the two this night. He had planned to enroll the teenager in school but learned that day that the young man’s monitoring services had been ended. “Today is the last day we work together.”

“You lie,” the boy says.

“I don’t want his services ended,” the mother says. “Why are you going to take away the one thing that’s been working?”

She wraps an arm around Mitchell. “How am I going to keep you?”