Detroit — Bobby Ferguson’s last remaining co-defendant pleaded guilty Friday in a surprise move just before a jury was seated in a $12 million bid-rigging trial.

The move by Ferguson’s colleague Michael Woodhouse to plead guilty to a conspiracy charge also came after U.S. District Judge David Lawson refused to let the West Bloomfield Township man stand trial separately from Ferguson.

Woodhouse, the former president of Ferguson’s company Xcel Construction, was indicted alongside Ferguson in September 2010. The case involves allegations that Ferguson obtained millions of dollars in city contracts by falsifying bids, illegally funneling proceeds and dumping debris from other jobs on the grounds of the old Herman Gardens public housing site on the west side.

The conspiracy to defraud the U.S. charge is punishable by up to five years in prison and a $250,000 fine. Sentencing is set for May 14.

Woodhouse is the sixth person to plead guilty in a criminal case that served as the undercard to the City Hall corruption trial...