State police have begun an investigation that will determine whether the controversy over Alfred Dowe's travel spending, which led to his resignation from the Roanoke City Council, will also lead to criminal charges.

The probe was approved recently by the state Attorney General's Office, which must authorize any investigation of an elected official, according to Buena Vista Commonwealth's Attorney Christopher Russell, the special prosecutor in the case.

Russell said Monday he hopes the investigation will be completed in about 90 days, which would allow him to decide whether Dowe should face charges by the end of the year.

Dowe resigned from the city council in February, after it was disclosed that he had billed both city and state taxpayers for the same expenses. The double-billing came to light after questions arose about Dowe's use of a city-issued credit card to run up a tab of nearly $15,000 last year for meals, travel and lodging -- almost as much as the rest of the council combined.

After being appointed special prosecutor in July, Russell decided additional investigation was needed beyond a report from the municipal auditor, which documented Dowe's double-billing. So he sought permission from the attorney general for a criminal investigation, which was approved within the past two weeks.

"There are a lot of documents to look at, obviously, both from the city and from Richmond," Russell said.

The documents from Richmond include travel expense vouchers that Dowe submitted to the Department of Criminal Justice Services, a state agency for which he was a board member.

Dowe sought reimbursement from the state for the costs of his mileage, meals and hotel stays associated with at least eight trips to Richmond to attend DCJS meetings, according to the vouchers.

But a second set of expense vouchers from the city show that Dowe put the same expenses on his city-issued credit card -- in effect billing the state for personal expenses that had already been covered by city taxpayers.

The double-billing involved about $3,000 from 2006 and 2007, according to the municipal auditor's report.

At first, Dowe defended his spending on meals and travel, saying it was evidence of him becoming a more engaged leader by meeting with community members and constituents. But he resigned shortly after the double-billing came to light.

Dowe's attorneys, John Fishwick and John Lichtenstein, released a brief statement on his behalf Tuesday.

"Mr. Dowe respects the process and he has cooperated with the audit performed by the City of Roanoke and he will likewise cooperate with any investigation by the Virginia State Police," it read. Since February, Dowe has reimbursed the city nearly $6,000.

Russell, who was appointed special prosecutor in part because Dowe once interned in the office of city Commonwealth's Attorney Donald Caldwell, said an investigator from the state police's Salem division has been assigned to the case.

Dowe's case marked the second time this year that a special prosecutor sought approval from the attorney general for an investigation involving a former member of the Roanoke City Council.

Earlier this summer, state police were authorized to investigate the placement of a newspaper political advertisement that attacked council candidate Court Rosen.

Brian Wishneff, a council member who lost his seat in a May contest in which Rosen was elected, has said he was involved in placing the ad. Wishneff said he gave a false name of Joe Smith as the person who paid for the ad, but said it was done at the prompting of a sales representative from The Roanoke Times.

At the time, Wishneff was working with a citizens group that was not registered as a political action committee as required by law, officials with the State Board of Elections have said. A member of the group, Citizens for Sensible Decisions, has said the group paid for the ad.

Botetourt County Commonwealth's Attorney Joel Branscom, the special prosecutor in that case, said Tuesday that a state police investigator has completed his first round of interviews and is now conducting follow-up sessions.

Because the case will involve more investigative manpower and legal research, Branscom said it was hard to say when it will be concluded.