If anyone knew why, they weren’t telling.

So Shonda Mason picked through the weeds that climbed over the jagged asphalt. She searched the leafy overgrowth swallowing a fence. She ran fingers over dirt to find the cave of a bullet hole.

She knelt to study the stains on the street.

Bushes revealed nothing.

The blood had washed away.

Rap. Rap. Rap.

She pounded on the back door of one of the houses that butt against the street.

Rap. Rap. Rap.

She imagined eyes behind the peephole, someone peeling blinds apart to see her face. No answer.

A woman drove up next door, and Shonda ran to the car.

“We was trying to find the spot where my son got killed,” she said, leaning in through the stranger’s window.

“He was laying in the street,” the driver said. That was all she would say.

Five months after Shonda’s 18-year-old son was found dead, his murder remained unsolved. His file sat within a stack of cases of other dead black teenagers, cases without evidence because witnesses wouldn’t talk.

Shonda knew that someone in the neighborhood had seen or heard about what happened that night. She understood why they wouldn’t speak about it. There was a code here. Before Eric was gone, Shonda had followed the code, too.

The code was never memorized or recited. It seeped into her from grade school.

“There are boundaries you don’t cross,” she said.

When someone kills your own, you kill them. You don’t rely on police sirens. You don’t tell what you saw. You handle it.

When Eric was 15, Shonda sent him to the hospital with a bullet in his stomach to get stitched up, belly button to chest. She taught him to ignore court subpoenas, to keep his name off court documents and police investigations, to say I don’t remember and I don’t know and I didn’t see anything.

The juvenile who police say shot Eric that time went on to be charged with killing two people. Eric never said a word.

Shonda sold crack cocaine her entire adult life, but he never told.

When a 17-year-old Eric was in a shootout, the police knocked on her door and she told the officers he wasn’t there.

She bailed him out on other charges. She followed the code.

Then Eric was dead, and all her black-and-white thinking turned gray. She’s been calling police and visiting their offices, trying to trust the uniforms she lied to most of her life, trying to help the same officers who once hunted her son.

Months into the investigation, the men Shonda is convinced killed Eric are still in the neighborhood. They post pictures on Facebook and Twitter with guns pointed at the camera, guns in their beds, guns coming out of their pockets. They say they would rather die than run their mouths, that talkers should die.

“I keep a pocket full of cheese to bring out all the rats,” one wrote.

She could see them driving down Dodds Avenue, pumping gas at the Kanku station or at the Bi-Lo getting a jug of milk. They’ve told her to stop blaming them publicly. But she won’t stop.

The police tell her they think she is right about the killers. Detectives tell her they are doing what they can. She tries to do the rest.

And she wonders about the fundamentals of the inner city, the code. Is it helping people?

Or is it burying them?