CHICAGO — Illinois Attorney General Lisa Madigan has expanded the state's investigation of mortgage lending practices, issuing subpoenas for documents from Countrywide, the nation's largest home lender.

The investigation follows a look at the loan origination procedures of the already-shuttered One Source Mortgage, many of which were provided by Countrywide. The AG filed suit against One Source in November for misleading borrowers, putting them into pay option adjustable rate mortgages they didn't know would adjust after only one month.

Countrywide's problems are further exacerbated by an SEC investigation into stock trades made by CEO Angelo R. Mozillo just before its stock took a dive earlier this year in reaction to the mounting subprime problem. The United States Trustee is also delving into several Florida borrowers' bankruptcy cases whose loans were serviced by Countrywide to find out if there was any misconduct in how they were handled.