HARRISBURG — A former state Senate leader and seven others have been charged in a “pay to play” case involving the Pennsylvania Turnpike, state prosecutors said today.

Attorney General Kathleen Kane said the eight are accused of criminal activity for their financial and political advantage. A grand jury heard evidence that cash, travel, entertainment and political contributions were secretly provided to public officials and political groups by turnpike vendors and their consultants, Kane’s office said in a news release.

The defendants include former state Senate Democratic Leader Bob Mellow, former turnpike chairman Mitchell Rubin and former turnpike chief executive Joe Brimmeier. Three former turnpike officials were also charged: George Hatalowich, 47, of Harrisburg, the former chief operating officer; Melvin Shelton of Philadelphia; and Raymond Zajicek of Tarpon Springs, Fla.

The other defendants are two turnpike vendors: Dennis Miller of Harrisburg, and consultant Jeffrey Suzenski of Pottstown.

The allegations include conspiracy, commercial bribery, bid rigging, theft and conflict of interest.

Kane said the grand jury found “substantial evidence” that Mellow directed an aide to help key contributors and supporters obtain turnpike contracts.

“The public has lost untold millions of dollars,” Kane said. “The greatest improper influence was exerted over the turnpike’s procurement process.”

The investigation began several years ago and has been conducted largely in secret.

In 2009, turnpike officials disclosed it had received a subpoena from state investigators.

More recently, a dispute over lawyer-client privilege between the attorney general’s office and the turnpike has been argued before the state Supreme Court. In that matter, the grand jury judge wrote in April that the investigation centered on “employment practices, procurement practices and the use of commission resources to conduct political activities.”