MARTINEZ -- The commander of a Contra Costa County drug task force and the head of a high-profile, Concord-based private investigative firm were arrested Wednesday on allegations they conspired to sell drugs, authorities said.

The revelation and potential blow to the credibility of any investigations involving the two are still being gauged.

Norman Wielsch, commander of the state Department of Justice's Central Contra Costa County Narcotics Enforcement Team, or CNET, and Chris Butler, who runs the investigative firm Butler and Associates, were arrested together in Benicia by federal agents Wednesday morning after an investigation that began in January, said DOJ special agent Michelle Gregory, spokeswoman for the Bureau of Narcotics Enforcement.

Both men were booked into County Jail in Martinez on as many as 25 suspected felony offenses, including possessing, transporting and selling marijuana, methamphetamine and steroids, and embezzlement, second-degree burglary and conspiracy.

Wielsch, a 49-year-old Antioch resident, is being held on $660,000 bail. Butler, 49, of Concord, is being held on $840,000 bail. They are both former veteran Antioch police officers who worked from the late 1990s to when they entered their respective positions.

Both men declined jail interview requests Wednesday. Media inquiries on Butler's website were referred to a Beverly Hills public relations agency, which said it no longer represented him.

Wielsch has been with the Bureau of Narcotics Enforcement for 12 years. To Gregory's knowledge, this is the first time a DOJ narcotics agent has been arrested under these circumstances.

"It's not reflective of our agency or our agents," she said.

There was no immediate word on who would replace Wielsch as head of the county task force, Gregory said.

As CNET commander, one of dozens of task forces run by the DOJ and staffed by officers from local police departments, Wielsch oversaw hundreds, if not thousands, of drug investigations in Contra Costa County.

Wielsch's arrest could have ramifications on criminal cases litigated in Contra Costa, said Concord private attorney Dirk Manoukian, a former deputy district attorney who has both prosecuted and defended individuals in CNET cases.

As the drug task force supervisor, Wielsch would traditionally have a limited role in investigations. As city budgets have dwindled, however, police agencies in the county have assigned fewer officers to the unit, which could have necessitated a more active role by Wielsch, Manoukian said.

"Your main concern from the standpoint of a prosecutor or a defense attorney is how centrally involved was he in the fact-gathering aspect in the case," Manoukian said. "With any fact that you can't corroborate through something else, or you can't prove through something else, you are going to have a credibility problem.

"Even though, right now, there are just pending charges, there are going to be police reports that allege serious felony conduct," Manoukian said. "If he's named as a witness (in another criminal case), a defense attorney will get those reports and (present them as evidence). They don't need a felony conviction."

Butler has made a name for himself as the head of his self-named private investigative firm, which he opened in 2002. Last year, his firm was adorned with national media attention for employing mothers as private investigators, touting their strengths in intuition and persuasion. The aptly called "PI Moms" are the subject of an upcoming reality television show, according to their website.

DOJ agents began investigating Wielsch and Butler in January after receiving a tip about potential drug sales, Gregory said. On Wednesday, agents were executing search warrants around Contra Costa County related to the case.

The Contra Costa District Attorney's Office will likely review and assess any charges brought against Wielsch and Butler, Gregory said.

No one reached at the District Attorney's Office on Wednesday would comment.

Staff writer Karl Fischer contributed to this report.