The first thing you need to know about these inspectors is that they tend to move fast.
Three men hop out of their white Chevy pickup and walk up to a shabby four-plex in the Dayton's Bluff neighborhood.
Two of them hit the backyard with flashlights, while the third, supervisor Rich Singerhouse, bangs on the front door.
"I don't see any lights on," he says. "Sometimes, you'll see lights go off and nobody will come to the door, so you know they're in there."
Singerhouse is in charge of monitoring abandoned and unsafe buildings. And part of his job is playing detective. At this property, the inspectors agree there are no signs of life.
They check garbage bins, scope out the driveway for vehicles, and peer inside the windows for TVs that may be turned on. Nothing.
Such visits have become more important, and more frequent, as the housing crisis continues. St. Paul has more than 2,000 registered vacant buildings, and about half of them are believed to have gone through some stage of foreclosure.
“Maybe it sounds mean or Grinch-ish, but the fact remains that there's a life-safety issue.”Steve Magner, manager of St. Paul's vacant building program
While the number of vacant homes is finally leveling off, the cost of inspecting, securing and maintaining empty buildings costs the city about $2.3 million a year.
That's because the wave of foreclosures -- 20,000 and growing in Minnesota -- has left cities with the responsibilities of shoveling sidewalks and protecting vulnerable buildings from copper thieves and gas explosions.
In recent months, St. Paul has enacted new reforms and expanded the vacant-building department to more aggressively tackle the problem. And checking for inhabitants is just one of many tasks for the inspectors.
If they find people inside, they break the bad news to unsuspecting families and homeowners they they need to move.
But program manager Steve Magner says the rules are there for a reason.
"Maybe it sounds mean or Grinch-ish, but the fact remains that there's a life-safety issue," he says. "We will fall on our swords for life safety."
On this night, Magner's team will visit nine buildings. Neighbors or code-enforcement officers have reported suspicions of people living there.
They'll also keep watch for vandals and urban explorers in abandoned landmarks, such as the former Hamm's Brewery and an old riverfront power plant known as Island Station -- two sites where St. Paul development dreams have languished.
The inspection crew cruises throughout the East Side and stops at a small white bungalow. A man in his 50s is standing outside in the cold.
He identifies himself as Rick Riley. He tells the inspectors that his son is renting out the house and he is just staying there for the night.
Riley asks, "What is all this about?"
"This is a vacant building," Singerhouse says. "It's a Category 2 status. It doesn't have the signoff yet. The owner knows this."
The officials explain that no one can live in the house until the landlord makes the repairs. The inspectors have already kicked out two families, but the owner continues to rent it out.
Bundled in his winter coat, Riley points out that it's cold. "I'm not getting kicked out, am I?"
"Well, probably not tonight," says Singerhouse.
Inspectors say most of the time, they don't evict people on the spot -- unless they are chronic offenders.
With the current foreclosure crisis, Magner says it's pretty easy for squatters to spot the abandoned homes.
"They see when someone moves out, or the papers are not being picked up, or the grass is not being cut, or the snow is not shoveled," he says. "A place might be going into foreclosure, but utilities are still on, so they will just go in there and set up camp."
In cases that involve repeat squatters, inspectors may issue a criminal citation, kick out the residents, and board up the buildings.
But they acknowledge that some succeed in eluding inspectors. Singerhouse points out new Christmas decorations adorning the back door of a house in the Midway.
"We've never been able to catch this guy," he says.
Many of the residents visited on the nighttime checks are renters. Magner says he's run into people who have unwittingly paid rent to swindlers who don't even own the vacant buildings.
But officials say at least half of the people who are caught living in vacant buildings are the rightful owners of those homes. In many cases, they're in a bind because can't afford to do the rehab while paying rent to live somewhere else.
Next on the stop is a modest house in the Frogtown neighborhood. An immigrant family recently bought the property while it was on the vacant list.
The husband and wife have plans to fix it up -- and even qualified for a $30,000 reconstruction loan from a neighborhood community-development group.
A man opens the door, revealing his kitchen. Pots are bubbling on the stove.
Magner asks the man, "Anyone speak English?"
He responds, "A little."
The inspectors ask to speak to the man's wife, whom they've met before. When she appears, her face turns sullen as soon as she sees Inspector Mike Kalis.
Kalis remains standing on the doorstep.
"Hi, remember me? We met at the police station that one day," he tells the woman. "You were supposed to get all the code stuff done. You guys haven't done that yet."
He tells the couple they need to call the community-development group about their loan: "You've got to get this work done, or we're going to have to move you guys out. OK?"
The woman apologizes and says she will make a phone call soon.
It's unclear how much of the conversation the couple understood. The inspectors say they'll come back next time with a Spanish-speaking interpreter.
They head back to the truck and look to see which vacant house -- perhaps "vacant" only in name -- is next on their list.