Chris Mathews' crew showed up this month to demolish one of the thousands of vacant homes destined for demolition as part of Detroit's grand plan to bulldoze its way to prosperity when a call from his office stopped them in their tracks: Someone was living there.

A middle-aged woman who watched the crew tear away the home's warped wooden steps the day before had called their company, Adamo Demolition, to point out she was living on the second floor, despite no power, heat or gas and a flooded basement.

"It was like a swimming pool. We would never have thought anybody was upstairs," said Mathews, noting that the incident cost his crew time because the demolition wasn't called off until after they had shown up with their equipment.

As Detroit carries out its plan to tear down tens of thousands of homes to combat blight and tailor the city to fit its population, which has dwindled to about a third the size of its 1950s peak, it will have to deal with an unknown number of squatters. Since the city doesn't allow occupied properties to be demolished, squatters who won't leave voluntarily and who have no previous connection to the homes have to be removed by police for violating the city's trespassing laws. That makes them a complication of sorts for the recovery of the city, which emerged in December from the largest municipal bankruptcy in U.S. history.

Clearing away as many vacant houses as possible as quickly as possible is a priority. Drug dealers often set up shop in them, bodies turn up in them and some houses have been sites of sexual assaults.

But for some of the approximately 16,000 homeless people in Detroit, the structures offer safety and shelter.

Michele McCray calls them "abandonminiums." McCray, 58, has been homeless for much of her adult life, yet she has had her pick of vacant houses to live in over the years.

"You look for one that's decent, already fixed up," McCray said from a homeless shelter where she stays when it's too cold to hunker down in a house without heat and other utilities.

"The first thing you do is cut the grass ... because the neighbors want to know who you are and what's going on over here. You have to maintain the property. Paint the place up, keep it looking good."

She sees it as a community service.

"A lot of people leave the door open because they want somebody to move in there," McCray said. "When you got somebody that's living in a place ... that keeps people from coming in, tearing the place up, stealing the fixtures. It cuts down on people starting places on fires, stealing your furnace."

A survey completed last year determined that more than 40,000 structures needed to be torn down. Another 38,000 had indications of blight and could be up for demolition.

Squatters aside, the city will not stop its fight against blight, said Craig Fahle, a spokesman for the Detroit Land Bank Authority, the agency overseeing the project.

"Illegal occupancy is an issue, but there is plenty of work to do with homes that are not occupied," he said.

About 10 percent of the houses Adamo goes out to demolish have squatters or evidence of squatters, according to Mathews.

Tiffany Tilley, a real estate agent, said about 20 to 30 percent of the more than 100 properties she has shown have had signs that someone had been squatting in them.

"When you're in the kitchen you might see food with plastic utensils in open jars," Tilley said. "There was an incident or two when there were feces stored in a bedroom in a bucket."

Squatters make it more difficult to show and sell properties, she said, referencing an east side house shown to investors about a month ago.

"We didn't go past the kitchen," said Tilley, 38. "It was evident someone had been in there or was still in there. There is always a risk of danger when you're dealing with someone who is squatting. I don't want to take that chance."

Latisha Johnson wants vacant houses in her East English Village neighborhood to be occupied, but not by squatters. She sees people living in houses that don't belong to them as part of Detroit's blight problem.

Johnson, a block captain and former leader of the neighborhood association, calls Detroit's squatting "an epidemic."

"I don't personally believe that any squatter is a good squatter," she said. "You don't know exactly what is going on in that house. You don't know if they are tearing up that house. The person has no responsibility and will not be held responsible for anything that occurs at that house."