Emmet Davitt, head of the State Prosecutor's office, in his office in Towson on July 26, 2012 . Davitt has brought corruption cases against many high-profile state officials, including Anne Arundel County Executive John Leopold. (Bill O'Leary/The Washington Post)

The no-nonsense state prosecutor held up a mud-caked campaign sign. He leaned forward in his chair as if ready to spring, then asked the witness a question in a booming baritone: Had she ever given Anne Arundel County Executive John R. Leopold permission to “take down, remove, deface or steal any of your signs?”

No, said the witness, Leopold’s onetime political rival. The answer helped the prosecutor, Emmet C. Davitt, portray Leopold as someone who misused political office and diverted public resources to orchestrate a campaign against enemies while leading Maryland’s fourth-largest county.

Davitt and his tiny band of investigators roam the state of Maryland with the unusual charge of pursuing election shenanigans and public corruption. The little-known Office of the Maryland State Prosecutor is believed to be the only one of its kind in the nation.

From a high-rise north of Baltimore, the bearded former high school guidance counselor takes on cases that are too politically sensitive for Maryland’s elected state’s attorneys or attorney general — and too small for federal prosecutors.

“He doesn’t have to answer to anybody; he’s just there to do the right thing,” said state Sen. Brian E. Frosh (D-Montgomery), who chairs the Senate Judicial Proceedings Committee. “They are on a hot streak.”

In the last year, Davitt has won convictions of two high-profile political consultants. His case against Prince George’s County Democrat Tiffany Alston led to her removal from the House of Delegates.

This month, Davitt is leading perhaps his highest-profile case yet. Leopold, a Republican, is charged with misusing his taxpayer-funded security detail to research political opponents and facilitate sexual liaisons. Leopold’s defense team has said he did nothing illegal.

That hasn’t stopped Davitt from doggedly pursuing the case in court, where salacious testimony has attracted reporters from more than a dozen media outlets with allegations of parking-lot trysts and police officers instructed to change Leopold’s urine bags during his recovery from back surgery.

Those dramatic tales contrast starkly with Davitt’s style in the courtroom: matter-of-fact and dry — even when he’s pressing witnesses for those sensational stories.

In other ways, Davitt is an unusual candidate for hard-charging political watchdog. One of 10 children in an Irish-Catholic family, Davitt grew up in Chevy Chase and is now the father of four.

He is the son of a Justice Department lawyer who spent a career building cases against Soviet-era spies.

But initially, Davitt chose a different path for himself: high school guidance counselor. He spent a year after college working with delinquent teenagers in the woods of West Virginia. Only much later, while working as a counselor at his alma mater, Good Counsel High School in Wheaton, did he enroll in night school to study law.

Davitt learned to think on his feet in the courtroom by handling drug cases in the Baltimore City State’s Attorney’s Office. His focus shifted to white-collar crime in the state Attorney General’s office, where he led the insurance fraud division. He then joined the general counsel’s office at the Public Service Commission to investigate complaints against utilities.

“He’s exactly the kind of person who is not going to get influenced or pushed around by political considerations,” said Doug Nazarian, Davitt’s former boss at the PSC and his neighbor in Catonsville.

Opponents have accused Davitt of being driven by politics, in part because of his appointment to a six-year term by Gov. Martin O’Malley (D). Other critics have questioned the wisdom of spending state resources to prosecute crimes involving relatively small sums of money.

But if the Leopold case is a measure, interest in Davitt’s caseload is running plenty high.

Davitt says it is not the size of the case that matters. And he denies any partisan bias; recent indictments of political figures have targeted Democrats and Republicans nearly equally, and Davitt says he hasn’t talked to O’Malley since taking the job.

“You have a chance to make an impact and send a message,” Davitt said in an interview before the trial got underway.

“We have a fantastic democracy, but people have to play by the rules.”

Created by the General Assembly in the 1970s to root out corruption, the office Davitt occupies was long considered ineffective and powerless. The turnaround began with Davitt’s predecessor, Robert Rohrbaugh. He hired more investigators and prosecuted former Baltimore mayor Sheila Dixon, who stepped down after her conviction for embezzling gift cards.

Davitt has continued that aggressive approach, Rohrbaugh said. Among those on Davitt’s team: two former Baltimore city police officers, a former Secret Service researcher and veteran deputy prosecutor Thomas M. “Mike” McDonough. The office has also been helped by the legislature, which recently empowered it to issue subpoenas for records and physical evidence.

Davitt only dabbled in politics before his appointment; he gave less than $300 to O’Malley between 2006 and 2009, according to campaign finance records.

Still, Davitt hears it from both sides of the aisle. Attorneys for Alston, who was found guilty of using $800 in General Assembly funds to pay an employee of her private law firm, have said that Davitt’s office pursued her in part because of her opposition to a redistricting plan supported by the governor.

Alston, who is African American, also asked why Davitt brought the case in majority-white Anne Arundel County instead of predominantly black Prince George’s. Alston’s conviction was struck after she completed 300 hours of court-ordered community service.

In the cases of Paul E. Schurick, the campaign manager to Republican former governor Robert L. Ehrlich Jr., and his consultant Julius Henson, defense attorneys accused Davitt of being on a “political witch hunt.”

In response, Davitt pointed out that the case was initiated by Rohrbaugh, who was appointed by Ehrlich.

“Regardless of who gets prosecuted, there will be someone who questions your purpose,” Davitt said. “Some days you feel a little thin-skinned, but . . . it comes with the territory.”

Schurick and Henson were convicted for their respective roles in approving and ordering an Election Day robo-call telling thousands of Democrats in Prince George’s and Baltimore to “relax” and not worry about voting. Schurick’s lawyer, A. Dwight Pettit, said the office and its law enforcement partners overreached in trying to link the calls directly to the state’s only Republican governor in a generation.

There are still limitations, however, for a statewide office with a $1.2 million budget and three prosecutors. His team relies on the Maryland State Police to execute search warrants and local state’s attorneys to work out immunity deals. And there are times when Davitt defers to the Maryland U.S. attorney’s office on complex corruption cases.

“We don’t see ourselves in competition,” Davitt said. “We’re all on the same team.”