LOS ANGELES -- Los Angeles Clippers owner Donald Sterling's team of lawyers has hired four private investigation firms to dig up "dirt" on the NBA's former and current commissioners and its 29 other owners, a source confirmed to ESPN.com.

The move was earlier reported by The Associated Press, citing a person familiar with Sterling's legal strategy.

Investigators were given a six-figure budget over the next 30 days to examine the league's finances, allegations of previous discriminatory conduct and compensation to past commissioner David Stern and current commissioner Adam Silver, said the AP source, who spoke Thursday night on condition of anonymity. The person wasn't authorized to talk publicly.

The person said the investigators also are looking into whether other owners made any off-color jokes, or racist or sexist remarks.

"The gloves are off, as they say," the person said. "Have them dig up all the dirt they can find."