The FBI and U.S Attorney’s Office have taken over investigating an East Bay law enforcement corruption scandal that could now involve out-of-state drug trafficking.

Three former Contra Costa law enforcement officers and a private investigator, charged with selling drugs, conspiracy, illegal weapons possession and setting up people for DUI arrests, may soon face federal charges as well, according to Contra Costa County District Attorney Mark Peterson.

Federal investigators will investigate whether the defendants sold drugs outside California, ran a brothel or were involved in growing marijuana, Peterson said. Those are angles to the case county investigators haven't had the time or resources to pursue, he said.

Those facing dozens of felony charges are: Norman Wielsch, former Contra Costa County Narcotics Enforcement Task Force commander; Concord private investigator and former police officer Christopher Butler; and former police officers from Danville and San Ramon Stephen Tanabe and Louis Lombardi

All remain free after posting bail, but they could be re-arrested by federal agents now that the case has been handed over, Peterson said. Wielsch, Lombardi and Tanabe are no longer law enforcement officers.

"As a direct consequence of these actions, three rogue police officers have resigned as police officers and will never again be entrusted with that responsibility," Peterson said.

The scandal grew so widespread – affecting multiple police departments, other law enforcement agencies and possibly crossing state lines – that it became too much for the county district attorney’s office to handle.

“With current budget constraints imposed upon my office, we do not have sufficient resources to adequately address the numerous areas of other possible illegal activity that need further exploration in this investigation and prosecution,” Peterson told a roomful of reporters at a Friday afternoon press conference in Martinez.

Another reason the case has escalated to a federal level is to avoid any appearance of bias, Peterson added.

"Our office has fulfilled its obligation to independently investigate and prosecute the illegal activities we have discovered to date," Peterson said. "However, the criminal investigation of these individuals must not only be independent in fact, but also, it must be completely independent in its appearance."

The state Department of Justice started the investigation on Jan. 25, looking into accusations of wrongdoing by Wielsch and Butler. County prosecutors jumped in on the case the following day, Peterson said.

In February, the district attorney's office filed its first battery of charges against Butler and Wielsch. (See a timeline of the main events in the case here.)

Lombardi, 38, was charged with conspiracy to sell drugs; possession of an assault rifle; possession of an SKS rifle; embezzlement; and receiving stolen firearms.

Those charges are part of a 38-count criminal complaint against Wielsch, Tanabe and Butler.          

Wielsch and Butler have been charged with conspiracy; selling methamphetamine, marijuana and steroids; and possessing methamphetamine, marijuana and steroids for sale.

Court documents say that Wielsch stole drugs from law enforcement evidence lockers and Butler arranged to have them sold. There are also accusations by Butler that Wielsch was involved in a brothel operation.

Tanabe, 47, is accused of being involved in steroid sales, according to court records.

Tanabe and Butler also have been charged in connection with a so-called "dirty DUI" scheme, in which Butler is accused of setting up men from multiple East Bay cities to be arrested for drunken driving. In some of the cases, Tanabe was the arresting officer.

Peterson said it's "very, very rare" for anyone to face federal charges without the county DA dismissing its own charges but so far there are plans for the case to continue at both levels.

The arrest of the three former police officers has already forced the District Attorney's office to toss out 15 criminal cases because of possibly tainted evidence. It's unclear how much more the scandal will unfold, Peterson added.

"We're hopeful that it's not any bigger than what we've uncovered ... but [already] it's gotten larger than we thought it would be," he said Friday.

– Bay City News also contributed to this report.