The eight-story baby cop in San Francisco is a protest. BiP, the anonymous muralist behind the painting, advertised as much halfway through the project when he posted the work in progress to his Instagram in October, calling the San Francisco Police Department out by name. “Let me be clear I am protesting you and all American police in regard to police brutality,” the artist wrote.

A month later, the Hayes Valley mural is complete — save for a few final touches — and the critique even sharper. Now, the chubby-cheeked child holds a handgun and wears a bright pink body cam that looks like something Fisher-Price might sell.

As pointed as the image might seem, BiP, in an exclusive interview with the San Francisco Chronicle, describes the mural as full of dualities. A protest, yes, but a humble and thoughtful one.

“My dream,” he says, “is if people want to go to a deeper place with me, there’s room for that.”

For years, BiP has had “Baby With a Handgun” in the back of his mind — literal sketches in his back pocket. Every time he thought to do it, though, he’d back out, pick another subject, one that felt less intense or provocative. He says it’s been a fight to get all of his murals up, even those that don’t critique the police.

But now was the time. In part because he knew the mural would be covered up within a year, hidden by another building under development. And also because he felt like he’d finally developed the sort of goodwill you need for a project like this.

“I’m one of the few artists who could maybe do something like this,” he says. That matters. “If you’re in the spotlight don’t blow it. Just try to do something.”

For the past few months, BiP, who is based in San Francisco, has set up shop in 22 Franklin St., the building that serves as his canvas. The anonymous artist answers the door with his mask off. He wears all white — white coveralls over a white hoodie — except for his black latex gloves and shoes that look gray but might just be covered in countless layers of paint. He smiles wider and talks faster than most.

There are rules for this interview: no audio recordings of his voice and no photographs of his face.

“I’m not Banksy,” he says. The anonymity isn’t so much about notoriety as it is — and he has a hard time articulating this — putting some space between himself and an art world that, for a long time, didn’t accept him. “I felt locked out of art, like it’s not for us,” he says. “It alienated me.”

Brown paper covers the floor throughout the small apartment-turned-studio, and in one room swatches hang on the walls and buckets of paint are stacked everywhere. “Do you want to mix some paint with me?” BiP asks. Then he jumps into a long description of the paint he uses, how it dries and the complexities of getting the colors just right. This sort of technical, granular stuff is what he spends most of his time on.

BiP doesn’t work with assistants, so it’s all him, crossing back and forth on the lift, mixing colors, painting some lines and then running downstairs to take it all in before going back up to make corrections. BiP is a perfectionist, but he also works alone because it means something to him that people know he’s so invested in the art he makes. “They know I touched every inch of the wall. They know it’s important to me.

“I try really hard,” he says, even if “sometimes I don’t always hit the mark.”

Before he settled on a final design for “Baby With a Handgun”, BiP says he sat down with family members of people killed by police violence. He spent a lot of time, too, thinking about how to make his statement.

“My job is not to sit here grinding an ax,” he says. And so, the mural is a conflicted one. You can see it in the image and in BiP’s public words. As he wrote recently on Instagram: “do you want to be the one making split second life or death decisions? do you think you can handle that every day with never a mistake? who could? I wouldn’t choose that. I’ll be the first to say I’m thankful for the ones that would. and I believe in my heart no one wants to be the one to unjustly kill another man, I believe that. but at the end of the day… the problem exists that police brutality is out of control. I’m sick in my heart for it.”

It took several drafts for BiP to get the image just right, to draw a face that was both a child’s and an adult’s, to juxtapose confusion and resolve, innocence and guilt. There are other dualities in the painting, too — look at the shadows, look at the warm and cool tones, the nods to masculinity and femininity.

Whether people notice the nuance is up to them.

In an email, Tony Montoya, president of the San Francisco Police Officers Association, wrote that it was “disappointing that a painting so big in size is limited in perspective. ... Sadly, this is an attempt to drive a wedge between police officers and the community we serve and it won’t succeed.”

On a recent afternoon, people passed in front of the mural, taking it in. The sky seemed ready to crack open and rain.

“That child looks very fearful,” said Karen Flood, 51, of San Francisco. She thought maybe he was worried about the job he’d been given, all the criticism that comes with it. “Yet your life is in danger every single day. It’s a split-second decision. I feel for the police. I feel for that child.”

Stefanie Klerkx and Chloe Davis, both 17 and juniors at International High School, said they’ve been watching the mural come together outside their classroom windows for the past few months.

“I think it’s a little confusing,” Klerkx said. “I’m not sure what the message is.” She paused. “I think it’s really well done.”

“Everyone at school, at least the faculty, have been pretty shocked by it,” Davis said. “I like that they’re using art as a form of protest.”

Others passed by but didn’t want to give their names because they worked for the city or said they were well-known lawyers or had police in the family. One woman called it “the best piece of public art I’ve seen in a long time.” Another man, who said he lived nearby, said his girlfriend didn’t like that it demeaned police officers.

As for the artist, after a few final adjustments, he’ll be done. “I try to listen very carefully, and I do the best job I can from my experiences,” BiP says. At the same time, “I don’t know if my job for the people is needing to be right.”

Once he has finished, the image will have to stand on its own, in conversation with the city around it.

Editor’s Note: The floor number of the artist’s temporary workplace has been deleted from this article.

Ryan Kost is a San Francisco Chronicle staff writer. Email: rkost@sfchronicle.com. Twitter: @RyanKost