A Sanbornville couple who supported tax protesters Ed and Elaine Brown during a nearly nine month standoff with federal agents have been arrested and charged with participation in tax fraud schemes in Massachusetts involving more than $16 million.

William Scott Dion and Catherine Floyd have been charged, along with several other defendants, with conspiracy to defraud the United States and obstructing the IRS for their part in creating a series of companies that federal prosecutors say were designed to obscure business finances from IRS scrutiny.

Dion is a member of the Constitution Rangers, a national anti-government group that Ed Brown once led. He and Floyd visited the Browns several times in 2007, when the Browns were holed up in their Plainfield home evading capture, according to comments made in court. The Browns were recently convicted of accumulating guns and improvised explosive devices and threatening violence against federal officials.

Both Dion and Floyd were called as defense witnesses during the trial. But both opted to exercise their Fifth Amendment rights rather than testify in the case. Judge George Singal told both Dion and Floyd that they would be asked about their history with the Browns, their visits to the Plainfield home, supplies they brought the couple and Dion's membership in the Constitution Rangers. Given those parameters, Dion and Floyd declined to testify.

The indictment, which was filed in Massachusetts, does not specify the motive for the crimes. But it accuses Dion, Floyd and others of operating several companies designed to commit tax fraud between 2000 and 2005. According to the indictment, about 150 employees participated in one scheme, which allowed them and their employers to avoid payroll, Medicare and Social Security withholding taxes. Under the scheme, court documents say, employers would give money to Dion and Floyd's company, then the company would pay employees without withholding taxes, noting their Social Security numbers or creating any IRS records.

Another scheme described in the indictment allowed customers to place large amounts of money in a "warehouse account" controlled by the defendants in exchange for fees. The defendants would then remove cash from the account and give it to their customers, court documents say. The indictment says that often large quantities of cash were wrapped in aluminum foil and mailed to avoid detection. The warehouse account enabled the customers to hide more than $16 million in assets from the IRS, prosecutors say.

The Browns refused to pay federal income taxes or withhold employment taxes on the grounds that there is no valid legal basis for the income tax. In 2007, they were found guilty of conspiracy to evade taxes on nearly $2 million in earnings from Elaine Brown's West Lebanon dental practice. The Browns placed their assets in trusts, stockpiled cash and gold, and were found guilty of breaking up large cash transactions into smaller pieces to avoid federal reporting rules.

According to court records, Dion and Floyd did not ask to be represented by lawyers, and they cross-examined witnesses at a detention hearing last week. They are being held on $250,000 bail. If they make bail, the judge has required them to allow their home to be searched for weapons, to turn over any Constitution Ranger badges, to refrain from entertaining groups larger than 10 people at a time and to use the names listed on their Social Security cards.

The maximum penalty for the conspiracy counts is five years in prison and fines proportional to any tax fraud. The maximum penalty for obstructing the IRS is three years in prison and $250,000 in fines. Any actual sentence would be determined with the help of federal sentencing guidelines, which recommend sentences based in part on the size of the total tax loss.

Dion and Floyd lived in Massachusetts at the time they are accused of committing the crimes. They now live in New Hampshire. Their co-defendants are Charles Adams of Norwood, Mass., Gail and Myron Thorick of West Warwick, R.I., and Gary and Kenneth Scott Alcott of Westborough, Mass.