Making the rounds at the Portland Public Library means sporadically checking inside the bathroom. It's not uncommon for security guard Marko Petrovich to uncover suspicious materials, like hypodermic needles and beer cans. Then the gumshoe work begins: Whodunnit? And sometimes whoever done it is still doing it. Long occupancy is call for suspicion. Spend too much time in the john and Petrovich will wind up in there with you, asserting in broken and unabashed English that "you not take shit forty-five minutes."

It's in the bowels of the library where people really sneak around, though. The biography section is tucked deep in the basement, a thicket of high shelves and narrow aisles — a natural hotspot for dubious behavior. There might be drugs slipped between the life stories of Fredrick Douglass and Stephen A. Douglas, and the orange carpeting seems to call to people looking for a nap or even sex, Petrovich says, lowering his voice to a whisper. Troll around with him long enough and you'll discover that folks do all kinds of things in the library. In a city of more than 66,000, there might be as many as 2,000 visitors every day. Indoor spaces that are actually open to the public are a rare find, and in a city like Portland, Maine — with months upon months of winter and an immense homeless population — the library becomes a living room of sorts. Keeping good guard of the library is delicate work. One must disrupt as few people as possible. Keeping the building safe and comfortable while at the same time truly public can be a precarious balance.

***

The Portland Public Library is situated in Maine's most densely populated and diverse zip code. Before its renovation in 2010, the building looked drab and almost foreboding from the sidewalk of Congress Street. Now it has an aeronautical façade, a vanity of bluish glass and a few too many right angles. But it's bright and warm inside, and has a pulsing, breathing life of its own. "Library is like small city," Petrovich muses. If that's the case, then the library staff is like a small civil-service division. This illusion is reinforced when library patrons address Petrovich as "Officer." It's an easy mistake, really. He dresses in police fashion — navy blue duty-wear — and his radio is rigged on his left shoulder above a metallic badge. There's also an array of security accouterments holstered to Petrovich's belt: flashlight, baton, handcuffs and pepper spray. Petrovich, thirty-six, is one of a handful of full-time security guards at the library, but he's the only one adorned like this. "When they hire me for security I tell them, 'O.K., let me do my job,'" he says.

Petrovich moves through the library with an assertive military posture. It's easy to imagine him as a young sergeant in the military out on patrol, in charge of others. He grew up in what was then the Socialist Federal Republic of Yugoslavia, a conglomerate of six republics on the Balkan Peninsula including Serbia, his motherland. It was his dream to become a police officer, but his family preferred the prestige of the military. Two years of service was mandatory in Yugoslavia, but Petrovich came from a string of military men — a grandfather, his father and uncles on both sides. So at age fourteen, Petrovich enrolled in a four-year military academy. He entered with a class of more than fifty and finished with only twenty-one. While military school was rigorous, he remembers that the toughest learning, the real schooling, came after.

Petrovich spent years on border patrol. His job was to "find suspicious things, people smuggling everything." He suspects that's why he's so good at catching wayward people in the library. "I know how they move, how they look at me, how they are expression in the face," he says. When he looks people in the eye, he reads them. "People can't lie to me much." But they can make a scene.

The typically quiet library is a vast, open space. When voices escalate, they carry. Even the smallest harrumph can become very public. Petrovich will often put his arm around misbehaving patrons and corral them to the security office to chat. It's a gentle and vulnerable gesture, and people seem to respond with concession and openness. To be an officer of the library is to be a steward of it. They must be civilized and caring toward the space, its resources, and, most importantly, its patrons.

Enforcement is a defensive act, not an aggressive one, and Petrovich learned the distinction between the two at a young age. "My grandfather telling me one day, 'You are soldier but you no murderer,'" he recalls.

Those words must have been bellowing in Petrovich's memory on the night that he deserted the Serbian army, fleeing the country. It was a flight to protect his life, and to protect other people from the killing he'd been tasked to do. Petrovich could fight soldier-to-soldier, or against anyone with a weapon. When there's fire on both sides, it is, as Petrovich says, "you or them." His job as a sergeant was to protect his soldiers, but he wasn't willing to do the job of killing innocent civilians. He had begun to refuse orders that looked to him like he was simply going into villages to murder hundreds of people just because they were Muslims. They were the kind of orders that make what Petrovich calls "bloody hands."

"I cannot do that," he says. "It is not my moral things. Not my code. Is not my job."

***

For Petrovich, the self-imposed uniform is essential. It has an effect on people, especially those up to no good. Enter the library intoxicated and you'll get a talking to — the warning — and be asked to leave for the day. Petrovich understands that "everybody gonna have booze and come in library." But if drunkards try to come in again and again, they'll be met with less and less compassion. Petrovich will say to them: "You know, man, how many times I talk to you? Four or five times? You out."

While there are plenty of people on permanent suspension, shorter time-outs are more common. "Sometimes I give people one week from the library," he says. Still, Petrovich would rather talk to people than suspend them, help them learn the rules and perceive the library as a privilege. But what he'd like most is to talk to patrons about other, worldlier things: Napoleon, the Civil War, the Romans. "History is my fashion," he explains. He'll talk to people about anything.

Besides the "duty job," the library offers Petrovich quite a bit. "I am a big fan of the maps. I like to know cities," he says. He studies city histories through old and new maps, along with historical accounts. That's how he's learned about the city he currently lives in: the 1866 great fire of Portland, the rebuilding of City Hall and the significance of the Soldiers and Sailors sculpture tribute in Monument Square. He knows the latticework of the library and the people who are supported by it. The library mirrors the population of the city, but here everyone is sharing chairs.

Rules don't mean that people can't just hang out. They can — and they do — so long as they don't impose on others using the space. "Share the Chair" signs mark popular seating areas, and indicate a ninety-minute cap on tables and chairs. That's long enough to get comfortable, but not too comfortable. Kick your shoes off or prop your feet up and you'll get a tap on the shoulder from Petrovich or another in his squad. Food and beverages are allowed in the library's front atrium. When the metal chair legs squawk against the hard flooring, the space sounds like a school cafeteria, drawing attention to the high concentration of people drinking orange juice. About two and a half vertical feet and a railing separate the atrium from the main floor, where brown pleather armchairs are configured in pairs, alternating in direction like the seats on a commuter train. But nobody seems to be in any hurry to go anywhere. On a weekday morning they're wearing sneakers, knees jutting out beneath the Press Herald, JanSport backpacks splayed at their feet.

The library has rules about personal hygiene, and Petrovich winces when he talks about some of the offenses, but he's swift and tender in dealing with them. "I try not just be jerk in the job," he says. "Try to help people. People need help sometimes." A few years ago a female library patron pooped on the floor. Petrovich got a trash bag to wrap around her waist, and then guided her to the security office for some clean clothes.

Libraries are a public good, but for many people the Portland Public Library is a necessity. It's a place for books and information, but it's also a place for intellectuals, old folks, lonely folks, mothers with babies and kids, teenagers after school, homeless people of all ages. It's everybody's refuge, and one of the few places where all of these people knock elbows.

When Petrovich opens the doors at ten a.m. there's a cluster of people waiting outside, chomping to get in. These first patrons of the day are often draped in bags and have been waiting for the library to open since the homeless shelters closed up at eight. Welcoming all kinds of people into the library pleases Petrovich, but he'd rather see everyone using the library resources — reading something rather than sleeping or using drugs or bringing in drama from the street.

***

The crown of Petrovich's peaked cap emerges from the stairwell ahead of him. He pauses at the top of the stairs, removes his cap and runs his fingers through his dark hair. He looks solemn and tired, and, for a moment, each of his thirty-six years are visible in the gray on his chin and faded scar on his right cheekbone. He looks like someone who's lived other epochs an ocean apart from the Portland Public Library, but while in the library it's clear how fully Petrovich prevails in the 83,000 square feet. Once in a while a librarian will have security cover a desk while they run to the bathroom or do something quick. Then they return to find that Petrovich has reset the computer desktop background to a portrait of himself. In the security office off of the library foyer there's an 8" x 10" Scotch-taped above the desk — Petrovich wearing his security uniform and posing in front of an American flag.

Sometimes he works the floor as security, but he also fixes toilets and hangs artwork and sets up for presentations. He'll do just about anything around the library that's no one else's job to do. On the eve of International Games Day, maintenance and security supervisor Paul Tetzlaff was building a giant KerPlunk in the library auditorium. KerPlunk is a game in which a bunch of colorful straws are inserted through holes halfway down a transparent plastic tube — a web of primary colors that suspends a stack of marbles. Players take turns removing a single straw strategically, careful not to let marbles tumble to the base of the tube. Tetzlaff oversees Petrovich.

Tetzlaff took a break from sawing away at the KerPlunk foundation to explain that a library suspension doesn't have any real teeth. "That guy who I issued a suspension for today might come back tomorrow," he says. When that happens, either the suspension process is repeated, or the security guards turn to something with a little more bite: a criminal trespass, or, for those in the business of issuing them, a "CT." Those who violate a CT are arrested, but before one receives a CT at the library, the security department needs to summon the police. Police officers come in pairs and spend the better part of forty minutes getting every side of the story, communicating with dispatch, getting case numbers and filing out the paperwork. All of that is changing though. It seemed to Tetzlaff that the police could be spending their time doing something that's, well, more important. Tetzlaff knows that issuing CTs is something his troops are equipped — and, in Petrovich's case, dressed — to handle.

In November, the city council made the decision to deputize Petrovich and two of his fellow security guards as constables. The word "constable" comes from the Latin word for stable, "stabulum." In the Roman Empire, a "stabuli" was an officer responsible for keeping the horses of the monarch. Nowadays constable is a title for anyone holding a particular office within the larger sphere of law enforcement. Beginning May 1, constables in Portland will be able to exercise a touch of real police jurisdiction within the walls of the public library. "Constable" has been a hot word amongst city council, the police department and the library administration. Opponents worry that the city order will disproportionately affect homeless people. Petrovich just appreciates that "constable mean honor."

***

As constable, Petrovich still won't be able to issue arrests, but he will be able to hand out CTs. Petrovich is intent on keeping the commons common, and that's part of what makes him well suited to work security. Finding a balance that keeps the library as public as possible means advocating for the public — as a whole population, and also one at a time, human-to-human. For Petrovich, it's work that comes with stalwart style and uncommon pride. "You don't need to respect me," he reminds patrons. "Respect this place. Respect this library is public."

About the Illustrator: Alex Nall is a cartoonist and teaching artist. His ongoing series "Teaching Comics" is a regular feature on Chicago Literati. He lives in Chicago.