SAN FRANCISCO -- A federal jury Tuesday convicted a former Danville police officer of six felonies for his role in the so-called "Dirty DUI" scheme to set up men for drunken-driving arrests that could be used against them in family court.

Stephen Tanabe, 50, of Alamo, appeared crestfallen as the court clerk read his guilty verdicts for conspiracy, and multiple counts of wire fraud and extortion.

The jury acquitted Tanabe of one extortion count that was tied to an allegation that he was paid in cocaine for arresting an Oakland software salesman in late 2010, but it convicted him of a wire fraud count related to text messages that prosecutors said pertained to the cocaine exchange.

Stephen Tanabe left, with his attorney Dan Russo, leaves Superior Court in Walnut Creek, Calif. Thursday April 21, 2011 after pleading not guilty on
Stephen Tanabe left, with his attorney Dan Russo, leaves Superior Court in Walnut Creek, Calif. Thursday April 21, 2011 after pleading not guilty on CNET-related charges. (Karl Mondon/Staff)

Tanabe, surrounded by family members, declined to comment after the verdicts. His attorney, Tim Pori, argued at trial that Tanabe never took any payment to make arrests, and was framed by former Concord private investigator Christopher Butler, architect of the "Dirty DUI" setups in which the estranged spouses of Butler clients were targeted.

"To go from an honest and respected police officer to a felon, it's devastating," Pori said. "This is devastating for Mr. Tanabe and his family."

Federal prosecutors presented evidence at the two-week trial that Butler, Tanabe's friend since they were both Antioch cops in the mid-1990s, gave Tanabe 3.5 grams of cocaine and a Glock pistol for facilitating three drunken-driving arrests in late 2010 and early 2011.

Butler said he attempted the scam about a dozen times: His employees, often attractive women, would entice the estranged spouses of his clients to get drunk at local bars, and then Butler would tip off a police officer in hopes the target would get a DUI that could be used against him in divorce and child-custody proceedings.

Tanabe was the only officer that Butler paid in connection with the scheme, Butler claimed on the witness stand.

Authorities started investigating the stings after Butler and Contra Costa Narcotics Enforcement Team Commander Norman Wielsch were caught selling stolen drug evidence in February 2011. They are serving eight and 14 years, respectively, for the drug sales, robbing prostitutes, making false arrests and other crimes.

Butler could have time shaved off the sentence for his testimony against Tanabe, which Pori argued motivated Butler to take down his old friend.

Although many people took part in the setups, Tanabe was the only one slapped with criminal charges. The end of his trial will trigger movement in about a half-dozen civil cases that have been filed in state and federal court by the "Dirty DUI" targets, all of whom have had their charges or convictions related to their tainted arrests dismissed.

Tanabe will be taken into federal custody at his Dec. 11 sentencing. Pori said Tanabe will likely be sentenced to between three and five years in federal prison. The government said each count calls for up to 20 years in prison.

Pori said he is planning appeals based on several issues, including whether the U.S. attorney's office aptly applied the law in charging Tanabe.

Contact Malaika Fraley at 925-234-1684. Follow her at Twitter.com/malaikafraley.