A contractor accused of paying a dozen Detroit school principals to get their business has pleaded guilty, the latest conviction in a corruption probe that's rocked the troubled district.

Norman Shy must repay $2.7 million to the district and could face more than five years in prison. As part of his plea Wednesday, the suburban Detroit man agreed to cooperate with federal investigators.

The government says the 74-year-old Shy paid about $900,000 in kickbacks. Twelve principals and an administrator have been charged.

Investigators say bogus invoices were submitted by school employees for chairs, paper and other supplies, some of which were never delivered.

The charges come while Michigan lawmakers are trying to come up with a bailout for the distressed school district, which is loaded with debt.