OAKLAND (CBS SF) – A private investigator involved in a Contra Costa County law enforcement scandal pleaded guilty to seven felony charges in federal court Friday that include drug offenses, conspiracy, extortion and illegal wire-tapping.

Christopher Butler, a 50-year-old former Antioch police officer, entered the pleas this afternoon 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.

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However, Butler’s defense attorney, William Gagen, said he believes Butler’s cooperation with the investigation into the corruption scandal involving his client and former CNET Cmdr. Norman Wielsh, 50, former Contra Costa sheriff’s Deputy Stephen Tanabe, 48, and former San Ramon police Officer Louis Lombardi, 39, will result in a lighter sentence.

“He feels extremely bad for a lot of reasons. A lot of people got hurt by this, especially his family,” Gagen said outside the federal court building today. “He knew it was time to be forthright and to try to get this over with as quickly as he could.”

His cooperation with federal investigators so far led to Butler’s plea deal and conviction today, Gagen said.

Butler told U.S. District Judge Saundra B. Armstrong Friday afternoon 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 Wielsch 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 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.

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

Addressing allegations of illegal wire-tapping, 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 also admitted to working with Stephen Tanabe, the former Danville police officer, to stage drunken-driving arrests of his clients’ spouses, who were often involved in custody battles or other legal disputes.

However, Assistant U.S. District Attorney Hartley West Friday 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 if asked against Wielsch and Tanabe if their cases go to trial.

He is set to be sentenced Sept. 11.

Butler’s plea entries came following the Friday morning 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.

“I need to start off by apologizing to my family,” he said tearfully, glancing at family members in the courtroom. “I can’t say how sorry I am for destroying some reputations in law enforcement.”

Lombardi received a three-year sentence, which he is set to serve in a federal prison in Oregon.

His attorney, Dirk Manoukian, had asked for Lombardi to be placed there to avoid being incarcerated with some of the criminals he dealt with as a police officer.

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