On a recent case, deputies were called to evict residents at a foreclosed building on North Spaulding Avenue, and arrived to find six families who were all paying rent to the landlord.

“All the time we paid every month, he never said nothing,” said Alma Aquino, who lived in one unit with her husband, their two children, and Mrs. Aquino’s mother and sister, for a rent of $850. “My husband tried to explain, but the sheriffs said we can’t talk, we need to evacuate.”

The family ended up staying, and Sheriff Dart, who has supported legislation to protect residents in foreclosures, soon stopped evictions.

Sheriff Dart said the evictions had taken an emotional toll on his staff. “It’s one of most gut-wrenching things we do, seeing little children put out on the street with their possessions. And the hard part is that the parent played by all the rules, and they’re being traumatized.”

Nationally, only about 10 percent of residents in properties with subprime mortgages  the ones most likely to go into foreclosure  are renters, said Eric Halperin, director of the Washington office of the Center for Responsible Lending, an advocacy group. But in some cities the figure is much higher. Daniel Lindsey of the Home Ownership Preservation Project run by Legal Assistance of Chicago, estimated that half of the city’s foreclosures involved renters.

“This is a big deal in the sense that it shows the pressures local governments are under when they’re forced to carry out those foreclosures and evictions,” Mr. Halperin said. “It’s another example of how the foreclosure crisis is overwhelming our institutions. Homeowners and renters can’t get the relief they’re entitled to under the law.”