WALNUT CREEK -- A Contra Costa County Judge on Wednesday dismissed all state criminal charges against four former officers tied to a vice squad corruption scandal in an effort to preserve a concurrent federal prosecution, attorneys said.

Judge Bruce Mills dismissed the 38-count felony complaint against Norman Wielsch, Christopher Butler, Stephen Tanabe and Louis Lombardi after a county prosecutor said the federal government's case would be compromised by a preliminary hearing that was scheduled to begin in Contra Costa Superior Court next month.

Mills dismissed the charges without prejudice, meaning the District Attorney's office can refile them in the future if needed.

"However, given the progress the federal charges have made, and the probable measure of justice imposed in those cases, we believe it is highly unlikely we will need to return to this court in this matter," senior deputy district attorney Harold Jewett said.

Wielsch, the former commander of the now-suspended Central Contra Costa Narcotics Enforcement Team, and Butler, a former Concord private investigator and Antioch officer in the 1990s, were arrested one year ago on suspicion of selling stolen drug evidence.

In the corruption probe that followed, more suspected crimes related to drugs, prostitution, theft and conspiracy came to light. Tanabe, a former Danville officer, was subsequently arrested on suspicion of conspiring with Butler to set up men for drunken driving arrests, and Lombardi, a former San Ramon officer, was arrested on drug, theft and conspiracy-related charges.

The dismissal Wednesday did not include an unrelated, misdemeanor domestic violence case against Lombardi still pending in Superior Court.

All four men are being prosecuted in federal court, with Lombardi awaiting sentencing after he pleaded guilty last month to nine felonies and misdemeanors. Butler and Wielsch are cooperating with investigators and are expected to take plea deals as well, and Tanabe is adamant that he had no knowledge of a DUI conspiracy.

Lombardi's attorney, Dirk Manoukian, said the dismissal request by the county prosecutor was not unexpected in light of the aggressive stance being taken by the U.S. attorney's office.

"They want a pretty severe punishment for everyone and higher sentences than the defendants would likely receive in state court," Manoukian said. "To put on a preliminary hearing in this case would take a couple of weeks with dozens of witnesses, and that would be a waste of the county's resources."

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