Starr didn't say much. He largely left the questioning of the first lady about missing FBI files to the 33-year-old Rosenstein, who is likely to be the next U.S. attorney in Maryland.
The moment illustrates how quickly Rosenstein was able to pull up a seat at the table of one of the highest-profile corruption investigations in decades, a remarkable feat for a junior lawyer now on track to become Maryland's top federal prosecutor.
Friends, former colleagues, retired federal investigators and opposing counsel describe Rosenstein, now 40, as both a dedicated father of two young girls who likes to ride his bike to work and a skillful lawyer who successfully mines witnesses for critical information and connects well with juries.
"Rod is probably the best trial lawyer I've ever seen in a courtroom," said Maury S. Epner, a Rockville attorney who served with Rosenstein in the U.S. attorney's office in Greenbelt in the late 1990s.
The unknown factor, several defense attorneys in Maryland say privately, is what kind of priorities Rosenstein would set for the office of 70 prosecutors trying cases affecting every corner of the state.
Rosenstein would inherit an office still shaking off the stormy tenure of Thomas M. DiBiagio, who resigned in December, five months after he wrote a widely criticized memo pushing his prosecutors for three "front page" indictments.
Supporters say Rosenstein has proved himself as a low-key leader who, in his current high-level Justice Department position, helped energize tax prosecutions around the country after he honed his skills in federal courtrooms in Maryland for four years ending in 2001.
Raised in suburban Philadelphia and educated in the Ivy League, he quickly won the respect of shoe-leather investigators and courtroom-savvy attorneys. They remember Rosenstein as a buttoned-down rookie prosecutor who nevertheless jumped into cases enthusiastically, often distilling complicated issues into simple concepts for his juries.
"Often we were supposed to call the assistant on duty, but we would just sort of call Rod up," said retired FBI Special Agent George Leyton, who supervised the bureau's violent-crime squad in Maryland. "I would say he was aggressive, not ambitious. He was the one who wanted to take the hard cases."
Though known by many for his conservative leanings, associates say they cannot point to instances where his political bent affected a case. A review of federal and state campaign finance records shows that Rosenstein has not contributed to political parties or candidates.
At Harvard Law School he was a member of the Federalist Society, and he has since attended events at its Washington headquarters. The organization promotes limited government and judicial restraint, serving as a breeding ground for conservative legal thinkers, including some of the more controversial recent nominees to the federal bench.
"I'm a Republican and Rod is too. We've both been to Federalist Society events," said Michael J. Madigan, a partner at the Washington powerhouse law firm of Akin Gump Strauss Hauer & Feld, who has also taught trial advocacy courses with Rosenstein at Georgetown University.
"But that doesn't mean anything," Madigan said. "Just because you go to the Federalist Society doesn't mean we all believe the same things."
Rosenstein declined to be interviewed for this article, citing his pending nomination before the U.S. Senate. A Justice Department spokeswoman also said her office would not be able to comment for similar reasons.
Unlike the recent controversy over nominees to the federal bench, Rosenstein's nomination by President Bush last month has had smooth sailing so far.
Maryland Sens. Barbara A. Mikulski and Paul S. Sarbanes, both Democrats, met privately with Rosenstein and returned their "blue slips" to the Senate to indicate they will not try to block the nomination. The Judiciary Committee and then the full Senate must approve the nomination, though Rosenstein could come to the office on an interim basis before those votes.
"He's smart and ethical, and experienced and knowledgeable," said Roger M. Olsen, who headed the Justice Department's tax division in the Reagan administration. "I'm just glad that people like him want to continue to serve."
Born in Philadelphia, he graduated from high school in the wealthy suburb of Huntingdon Valley just north of the city. At the University of Pennsylvania's Wharton School, he worked on a campus literary magazine and joined the pre-law society.
In 1986, with a degree in economics, he graduated summa cum laude and Phi Beta Kappa and left for Harvard.
He clerked for Judge Douglas H. Ginsburg of the U.S. Court of Appeals for the District of Columbia Circuit, shortly after the jurist's Supreme Court nomination sank in 1987 when Ginsburg admitted smoking marijuana in the 1970s.
Despite his political leanings, Rosenstein held several jobs in the Clinton administration's Justice Department before becoming associate independent counsel for what is commonly known as the Whitewater investigation.
Rosenstein was on the only case that Starr's office successfully prosecuted at trial - securing fraud convictions against then-Arkansas Gov. Jim Guy Tucker and Clinton friends James and Susan McDougal, who were involved with Madison Guaranty Savings & Loan Association in Little Rock, Ark.
"We certainly formed a close bond," said Amy J. St. Eve, who worked as a prosecutor with Rosenstein on the case before she became a federal district judge in Chicago in 2002.
"One of the great talents I think he has is that he's never hesitant to question any decision. He really thinks through everything from every angle," she said.
The tight-knit group of bright lawyers working for Starr were all transplants, living apart from their families for months at the same apartment complex. They were also cautious, according to St. Eve, about socializing in Little Rock, where their faces were known on the street.
"He was a little more tentative than I was, but I was known for being very aggressive in my district," said W. Hickman Ewing, the deputy independent counsel in charge of the Little Rock office, who had previously served for a decade as U.S. attorney in Memphis, Tenn.
But Ewing also described Rosenstein as a level-headed and talented attorney who thrived despite the pressure-cooker office that received news media scrutiny almost every day.
"I respected him more and more as time went on," said Ewing, who is now retired.
Known as one of the "youngsters" in the office of more than a dozen attorneys, Rosenstein prepared and questioned witnesses in the part of the trial case against Tucker. After the jury convicted Tucker and the McDougals, the prosecution team joined Starr for a celebration with cigars. Susan McDougal served 18 months for civil contempt for refusing to testify against President Bill Clinton before the Whitewater grand jury. She was later pardoned by Clinton as one of his last acts in office.
Taking more of a lead role, Rosenstein supervised the independent counsel's investigation of allegations that the White House wrongly obtained background reports from the FBI. Hillary Clinton was never implicated in the case; she only met with prosecutors as a witness, according to the independent counsel's final report.
Rosenstein left before the investigation by Starr turned to President Clinton and his involvement with White House intern Monica Lewinsky.
When he arrived in Maryland as an assistant U.S. attorney, Rosenstein worked largely out of the office in Greenbelt. A review of more than 100 docket summaries showed that he prosecuted a full range of cases, from mail fraud to murder.
'A hard worker'
"I can tell you that he did very good work," said Maryland Court of Appeals Judge Lynne A. Battaglia, who hired Rosenstein when she served as Maryland's U.S. attorney in the 1990s as a Democratic appointee. "A federal prosecutor has to be someone who exercises good judgment. He has very good judgment, and he's a hard worker."
Leyton, the retired FBI agent, remembers how much his career meant to Rosenstein's family: His parents sat in the front row for his first trial.
Retired Internal Revenue Service investigator Marion J. Siara, who spent 28 years investigating tax fraud, found he couldn't get a prosecutor to take up his investigation of Nigerian immigrants who were filing dozens of false returns and receiving hundreds of thousands of dollars in fraudulent refunds.
Rosenstein, Siara said, came to the rescue.
He brought the case to court in Maryland, winning two guilty pleas and scoring two convictions at trial, according to Siara, who was based in the IRS' Indianapolis office.
"One of the witnesses was a wife of one of the defendants," Siara said. "I had never been able to turn her, but with a phone call he was able to get her to say that she had been threatened by her husband."
One of his highest-profile cases as an assistant U.S. attorney was the prosecution of a teller for her role in the 1998 armed robbery of the College Park credit union where she worked. It was one of the largest robberies in Maryland history.
Rockville attorney Epner, who co-chaired the prosecution in the case, said Rosenstein's closing wrapped up all of the elements of the case and still made the legal issues understandable.
"Ladies and gentlemen, April Montague played her role very well and she deserves a reward for her performance," Rosenstein told the jury in his summation. "The reward you should give her, ladies and gentlemen, is a verdict of guilty on both counts, because the facts add up to only one reasonable conclusion."
In his current job in Washington, Rosenstein has had authority over most federal prosecutions of tax violations.
For years, critics have complained that the IRS has consistently failed to investigate cases in a meaningful way. The number of tax prosecutions had dropped drastically, from 1,541 in 1981 to 538 in 2003, according to law enforcement data collected by Transactional Records Access Clearinghouse at Syracuse University.
"And they've really gone after a lot of the mom-and-pop type of cases in the ones they choose," said David Burnham, a former New York Times reporter who now runs TRAC.
But according to both Burnham's numbers and internal Justice Department statistics, the trend has been reversed, showing a slight uptick in prosecutions during the most recent period of Rosenstein's tenure as principal deputy assistant U.S. attorney for the tax division.
"There is a trend in being more aggressive," Rosenstein told The Arizona Republic in April. "There was a period where the IRS was not sufficiently aggressive and we worked more on customer service."
His office also revived the use of civil injunctions, including the case brought last month against John Baptist Kotmair Jr. for allegedly selling tax-fraud schemes through his Westminster-based Save-A-Patriot Fellowship.
The strategy has been lauded by prosecutors as a way to recover illegal gains without having to wait for sometimes-lengthy criminal investigations to conclude. In 2000, the department brought no injunctions of this kind in tax cases; by this month, prosecutors had brought a total of almost 150 in the last four years.
As U.S. attorney in Maryland, Rosenstein will face challenges from all corners, including prosecuting violent crime and picking up cases that failed to yield convictions in state court.
Among the most prominent may be the fate of Solothal Thomas.
The 'Itchy Man' case
Thomas, known on the streets as "Itchy Man," is alleged by police to have been one of the most violent "enforcers" in Baltimore. Several months ago, he was indicted on federal conspiracy charges that could carry the death penalty.
Thomas was profiled in The Sun's 2002 series "Justice Undone," which examined flaws in Baltimore's criminal justice system. He is notorious among local police and prosecutors for being accused of two killings and 12 attempted killings, but never being convicted.
Rosenstein will need to decide whether to seek the death penalty against Thomas, who is scheduled for trial in January.
Over the years, Rosenstein maintained strong ties to legal life in Maryland. In 2003, he applied and was short-listed for an opening for a federal district judgeship in Greenbelt that eventually went to Roger W. Titus.
Rosenstein lives in the Washington suburbs with his two girls and his wife, a government attorney who had been a federal prosecutor in Washington.
Once or twice a week, he rides his bike from his Bethesda home to his office at the Justice Department headquarters on Constitution Avenue.
Colleagues say that despite his substantial accomplishments, Rosenstein remains modest and self-effacing.
"He believes in the down-to-earth approach," Madigan said. "People in our profession can be a tad on the self-important side. We were together recently, and you're supposed to say what your background is for the lawyers in the program.
"When it came to Rod, he didn't even say that he had been nominated for U.S. attorney. Someone else had to mention it."
His career move back to Baltimore certainly isn't about the money. He would add only $100 to his $140,200 salary as U.S. attorney, according to the Justice Department.
And it's not about getting a better view.
From his fourth-floor office at the Justice Department, Rosenstein can look east through 8-foot-high windows to see the National Archives, the dome of the Capitol and finally down to the Supreme Court.
But he's already told friends he's eager to trade it all in - for a chance to gaze at a sliver of Baltimore's Inner Harbor from the office of the U.S. attorney.