FBI investigation in Oakland expands to its police department

OAKLAND, Calif. (KGO) -- The FBI's investigation into Oakland Mayor Sheng Thao and the Duong family is expanding. It has now subpoenaed the Oakland Police Department.

"This is significant because we appear to be entertaining a massive corruption investigation that is currently underway by the grand jury, at the instruction of the Department of Justice," says professor Greg Woods, with the Department of Justice Studies at San Jose State University.

Professor Woods says the subpoena is not necessarily to uncover any wrong doing by the Oakland Police Department. But rather, to see if any victims have filed complaints related to those under investigation.

"They would call the Oakland Police Department to report such an encounter, such as potential victimization," explains Woods.

TIMELINE: FBI political corruption investigation involving Oakland Mayor Sheng Thao, Duong family

Professor Woods suggests it may also be to establish a timeline. A subpoena allows the FBI to learn about the nature of the calls and what, if anything, was reported. That could determine probable cause.

"To, in fact, charge somebody with a crime and place them into custody. And then to continue this judicial process to hold individuals accountable," he says.

The FBI and the Oakland Police Department did not return request for comment. But the Bay Area News Group is reporting that a subpoena was issued to OPD to turn over all internal phone directories since the beginning of march. And all police reports involving the Duong family from the beginning of April.

In June, the FBI raided Mayor Thao's house, and homes belonging to members of the politically-influential Duong family. They own California Waste Solutions, a recycling company that operates in Oakland. As the ABC7 I-Team reports, the investigation may be linked in part to a campaign contribution laundering scheme.

VIDEO: Report alleges 'campaign contribution laundering scheme' involving Oakland mayor, city officials

Report details Andy Duong family's political ties and who they donated to, including Oakland Mayor Sheng Thao whose home was raided by the FBI.

The FBI has also subpoenaed the city of Oakland allegedly looking into sources of funding.

"It is also an investigation into the transparency of how it is that money moves through the support and donations to the political campaigns that impact the city of Oakland," says Woods.

No charges have been filed. And Mayor Thao has denied any wrongdoing.

Woods says this type of FBI grand jury investigation could go on for months, if not into next year.