A San Ramon attorney has been indicted after being linked to the "dirty DUI" case that led to the arrest of police officers across Contra Costa County and the disbanding of the county's narcotics enforcement team.

Mary Nolan, 60, was charged Tuesday with unlawfully intercepting communications and tax evasion, according to federal officials.

Nolan was arrested at her home in Oakland, prior to making her first appearance in federal court. An indictment claims that Nolan, owner of The Law Offices of Mary Nolan in San Ramon, "conspired to and procured another person to unlawfully intercept wire, oral and electronic communications" between August and September 2007.

Specifically, the indictment said Nolan referred clients to private investigator Christopher Butler for Butler to install bugs in the cars of her clients' spouses or significant others. The indictment also claims that on numerous occasions, Nolan and her staff -- acting on Nolan's instructions -- used the bugs to eavesdrop on conversations to use that information to help in Nolan's client's legal proceedings.

In 2009, Butler admitted to working with former Contra Costa Sheriff's Deputy Stephen Tanabe, a former Danville officer, to stage drunken-driving arrests of his clients' spouses, who were often involved in custody battles or other legal disputes.

In addition, Nolan's indictment claims she "willfully attempted to evade and defeat a large part of her income tax due and owing by causing false tax returns to be filed with the IRS from 2005 through 2008."

In all, Nolan didn't report more than $1.8 million in earnings and bilked the IRS out of nearly $600,000 in taxes, according to a news release.

She could receive up to five years in prison and $250,000 in fines on each of the tax evasion charges and the same amount of prison time and fines for unlawfully intercepting communications.

After posting a $50,000 bond, Nolan will be released on a bond that includes $250,000 of security in the form of a deed that must be posted within two weeks. She is scheduled to appear in federal court in Oakland on Sept. 25 for arraignment.

In May, Butler, a 50-year-old former Antioch police officer turned private investigator who became involved in a Contra Costa County Dirty DUI law enforcement scandal, pleaded guilty to seven felony charges in federal court that included drug offenses, conspiracy, extortion and illegal wire-tapping.

He entered the pleas in connection with drug possession and sales, robbery, conspiracy against civil rights, extortion and other crimes he committed as a private investigator working with members of the Contra Costa County Drug Enforcement Team, or CNET, over a period of about four years.

In court, Butler described how he illegally installed between 75 and 100 listening devices in the vehicles of his clients' spouses to secretly record their conversations for his clients and their attorneys.

Butler's defense attorney, William Gagen, said he thinks Butler's cooperation with the investigation into the corruption scandal involving his client and former CNET Commander, Norman Wielsh, 50, Tanabe, 48, and former San Ramon police Officer Louis Lombardi, 39, would result in a lighter sentence.

Butler told U.S. District Judge Saundra B. Armstrong that between June 2009 and February 2011, he teamed with Wielsh to sell large quantities of marijuana, methamphetamine and steroids obtained during CNET searches of suspects' homes.

Working with an employee in his Concord private investigation firm to sell the drugs, Butler and Wielsch split the proceeds, which totaled no more than about $30,000, according to Gagen.

On several occasions, Butler drove Wielsh to the Contra Costa County Sheriff's Office evidence facility to take drugs from lockers and keep them for sale, Butler told the court.

The private investigator also admitted to conspiring with Wielsch to stage illegal search-and-seizure operations of prostitutes the CNET commander found via online ads on websites such as Craigslist.com and Redbook.com.

The pair met the prostitutes at hotels in San Ramon and throughout the Bay Area, with Butler acting as the john. After knocking on the door, Wielsh would burst in the room, show his police badge and seize the woman's possessions and cash, Butler said.

In one such incident in the summer of 2010 at Homestead Studio Suites in San Ramon, the pair robbed a prostitute and her madam of more than $10,000, cellphones and car keys, he said.

The private investigator also worked with Wielsh in a 2009 incident in Pleasant Hill to stage an arrest of someone whose mother, a client of Butler's, suspected he was selling drugs. The pair seized thousands of Xanax tablets during the illegal search and seizure, attorneys said.

Butler also pleaded guilty to helping Wielsh in 2009 open an illegal massage parlor where the masseuses provided sexual services. He admitted to collecting more than $10,000 from the women working there in exchange for protection from Wielsh.

However, Assistant U.S. District Attorney Hartley West agreed to dismiss an extortion charge against him in connection with that crime after discussion with Armstrong, who said she did not believe his role in the "dirty DUI" scheme fit the legal definition of extortion.

Gagen said the dismissal of that charge would not affect Butler's sentence, which will likely fall between 10 and 14 years in prison.

As part of his plea agreement, Butler also agreed to testify against Wielsh and Tanabe if their cases go to trial.

Butler's plea entries came following the sentencing of former San Ramon Police Officer Louis Lombardi, who pleaded guilty earlier this year to his role in the CNET scandal, which included selling marijuana, and stealing nearly $50,000 in cash and property during searches of suspects' homes.

Lombardi received a three-year sentence, which he is serving in an Oregon federal prison.

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