Two more Northern California real estate investors pleaded guilty to rigging foreclosure auctions.

Justice Department investigations in the state netted 24 bid rigging guilty pleas to date.

The latest two, Douglas Ditmer and Keith Slipper paid other conspirators not to compete for foreclosed properties being auctioned on county courthouse steps from July 2008 through 2011. They were able then to acquire homes at suppressed prices. The two also committed the fraud in private auctions open only to members of the conspiracy, according to court documents.

"By agreeing not to compete with one another in the bidding process, these investors illegally profited and undermined the integrity of the real estate market," said Scott Hammond, deputy assistant attorney general at the DOJ. "The conspiracy eliminated competition and prevented lenders and distressed homeowners from getting fair market prices for their property."