SEE ALSO: Ex-Sen. leader, 7 others charged in Turnpike probe  |  A look at 'pay-to-play' turnpike case defendants

HARRISBURG - Four people accused in a corruption investigation of the Pennsylvania Turnpike have turned themselves in to be arraigned.

All four were released on $100,000 unsecured bond Wednesday. Two of the other four defendants are due in court Thursday, one is in prison in South Carolina and the other is in Florida.

Prosecutors say the charges relate to a four-year grand jury investigation into a "pay to play" scheme in which contract-hungry vendors gave turnpike officials gifts and made political contributions.

The defendants include Bob Mellow, a former Democratic floor leader in the state Senate, and Mitchell Rubin, the turnpike's former chairman.

Mellow's currently serving a corruption sentence at a federal prison in South Carolina.