INDIANAPOLIS -- Two more men have been arrested in connection with a nationwide car theft ring based in Indianapolis, federal authorities said.

Derrick Sanders, 32, and Darren Stephens, 45, both of Indianapolis, were arrested on charges of conspiracy to commit mail fraud after warrants were issued last week.

Sanders and Stephens are accused of working as sales people for a group that stole vehicles, altered the vehicle identification numbers, created counterfeit titles and then resold the vehicles for profit across state lines, said U.S. Attorney for the Southern District of Indiana Timothy Morrison.

Five men -- Christopher Wells, 45, of Indianapolis; Tommy Thompson, 48, of Indianapolis; Fred Bear, 39, of Avon; Francis Coleman, 41, of Maryland; and Carl McCreary, 48, of Alabama -- were arrested in December and charged earlier this year.

The investigation began in 2009 when police said a person came into a Shelbyville Bureau of Motor Vehicles branch, presented a title from North Carolina and wanted to re-title the vehicle, but one of the documents was flagged as suspicious.

The federal investigation began shortly thereafter, spanning seven months and recovering nearly 30 stolen vehicles, Morrison said.

Nine search warrants were executed at locations in Indiana, Alabama and Washington, D.C., including at Thompson's Indianapolis home.

Authorities said the men ran the scheme between January 2007 and December 2009.