Six people pleaded guilty yesterday to federal charges related to an alleged $4.6 million tax fraud that the government says was orchestrated by a Blue Bell lawyer.

Those who pleaded guilty yesterday before U.S. District Judge J. Curtis Joyner were among 11 indicted last month. Prosecutors have described the case as the largest tax fraud in the region in recent memory.

The lead defendant, lawyer Bernard Jay Bagdis, is accused of creating shell corporations, a fictitious foreign bank, and a basement-waterproofing company to hide $23 million income from the IRS. The loss to taxpayers was $4.6 million, officials said.

Bagdis, 58, and four others have pleaded not guilty. Each is free on bail pending trial next year.

The six who pleaded guilty yesterday are cooperating with the IRS, FBI and Postal Service investigation. They are:

Kenneth W. Klinger, 57, of Perkiomenville, part-owner of Basement Doctor Waterproofing Co. He admitted working with Bagdis to avoid $393,000 in taxes.

Stephen Schulz, 43, of Richboro, also a part-owner of Basement Doctor, who avoided taxes of $253,590.

Michael S. Klein, 36, a Warrington lawyer, who avoided about $74,000 in taxes.

Kathleen Williams, 46, an administrative assistant from Pottstown who worked for Bagdis, and avoided $61,000 in taxes.

William K. Acosta, 52, a Gilbertsville businessman, who avoided $167,000 worth of taxes.

Helen M. Gramaski, 69, of Ardmore, the owner of a commercial cleaning business, who avoided $60,000 in taxes.

According to Assistant U.S. Attorney John Pease, the advisory federal sentencing guidelines in this case recommend 2- to 4-year sentences for Schulz and Klinger. The guideline range for the others is at least a year.

Steven Hedrick, 36, of Dover, Del., who owned a debt-collection service, and allegedly avoided $500,000 in taxes, is scheduled to plead guilty in January.

Contact staff writer John Shiffman at 215-854-2658 or jshiffman@phillynews.com.