WASHINGTON — Officials in 49 states and the District of Columbia have launched a joint investigation into allegations that mortgage companies mishandled documents and broke laws in foreclosing on hundreds of thousands of homeowners.

The states' attorneys general and bank regulators will examine whether mortgage company employees made false statements or prepared documents improperly.

Alabama was the only state not to join the investigation.

Attorneys general have taken the lead in responding to a nationwide scandal that's called into question the accuracy and legitimacy of documents that lenders relied on to evict people from the homes. Employees of four large lenders have acknowledged in depositions that they signed off on foreclosure documents without reading them.

The allegations raise the possibility that foreclosure proceedings nationwide could be subject to legal challenge. Some foreclosures could be overturned. More than 2.5 million homes have been lost to foreclosure since the recession started in December 2007, according to RealtyTrac Inc.