WASHINGTON – Federal authorities are investigating allegations that a California defense contractor arranged for a Washington-area limousine company to provide prostitutes to convicted former congressman Randy “Duke” Cunningham, R-Calif., and possibly other lawmakers, sources familiar with the probe said Friday.

In recent weeks, investigators have focused on possible dealings between Christopher Baker, president of Shirlington Limousine and Transportation Inc., and Brent Wilkes, a San Diego businessman who is under investigation for bribing Cunningham in return for millions of dollars in federal contracts, said one source, who spoke on condition of anonymity.

Baker has a criminal record and past financial difficulties, public records show. Last fall, his company was awarded a $21 million contract with the Department of Homeland Security to provide transportation, including limo service for senior officials.

The Cunningham investigation’s latest twist came after Mitchell Wade, a defense contractor who has admitted bribing the congressman, told prosecutors that Wilkes had an arrangement with Shirlington Limousine, which in turn had an arrangement with at least one escort service, one source said. Wade said limos would pick up Cunningham and a prostitute and bring them to suites Wilkes maintained at the Watergate Hotel and the Westin Grand in Washington, according to the source.

Cunningham resigned from Congress after pleading guilty last November to accepting $2.4 million in bribes from four coconspirators, including Wilkes and Wade. The former lawmaker was sentenced to eight years and four months in prison. Wade pleaded guilty to his part in the scheme in February and is cooperating with investigators. Wilkes has not been charged.