The investigation of a scheme to plunder corpses for transplantable body parts has been broadened as prosecutors secured plea deals with seven funeral home directors who have agreed to cooperate.

The unidentified directors secretly pleaded guilty to unspecified charges in the probe of what investigators say was a plot to harvest bone and tissue and sell it to biomedical supply companies, Brooklyn District Attorney Charles Hynes said yesterday.

The seven entered their pleas in closed courtrooms and their names were withheld, but defense attorneys said that among those cooperating was the director of a funeral home that took parts from the body of "Masterpiece Theatre" host Alistair Cooke, who died in 2004.

Hynes also announced that a grand jury had voted to bring additional charges in the case. A new indictment adds allegations involving 14 looted bodies at funeral homes in Manhattan, the Bronx, and Rochester, N.Y.

Prosecutors said more arrests were possible.

The four original defendants in the case pleaded not guilty yesterday to enterprise corruption, body stealing, and other charges in the new indictment. They face up to 25 years in prison.

Prosecutors allege Michael Mastromarino, a former oral surgeon, and three other men secretly removed skin, bone, and other parts from as many as 1,000 bodies from funeral homes. He allegedly made millions of dollars by selling the stolen tissue to biomedical companies that supply material for common procedures, including dental implants and hip replacements.

Prosecutors said they unearthed evidence that death certificates were falsified.

Cooke’s age was recorded as 85 rather than 95 and the cause of death was listed as heart attack instead of lung cancer that had spread to his bones.

Other evidence includes X-rays and photos of exhumed cadavers showing that where leg bones should have been, someone had inserted white plastic pipes — the kind used for home plumbing projects, available at any hardware store. The pipes were crudely reconnected to hip and ankle bones with screws before the legs were sewn back up.

Mastromarino, owner of Biomedical Tissue Services of Fort Lee, N.J., has denied any wrongdoing, saying funeral parlor directors were responsible for getting consent for donations.

At the news conference, Elizabeth Johnson, of Newton, Mass., described her shock when investigators informed her that they believe her 67-year-old cousin’s body was secretly carved up for parts in 2003 at a Brooklyn funeral home.

"We thought we had given him a nice ending," she said.